WASHINGTON — The announcement by Justice John Paul Stevens on Friday that he would retire at the end of this term gives President Obama the rare opportunity to make back-to-back appointments to the Supreme Court during the first two years of his presidency.

But it also presents Mr. Obama with a complex political challenge: getting a nominee confirmed in the thick of a midterm election season, when Republicans, fueled by the intensity of their conservative base, are angling to knock him down, and Democrats, despite having lost their 60-vote supermajority in the Senate, are eager to flex their muscles after passing a landmark health care bill.

Justice Stevens’s announcement, delivered to the White House on Friday morning in a one-paragraph letter that began “My dear Mr. President,” set off an immediate scramble among the parties and a raft of advocacy groups that have been assembling dossiers on potential successors.

The three leading candidates — Mr. Obama is considering about 10 names all told, the White House says — present the president with a spectrum of ideological reputations, government backgrounds and life experiences. His choice will shape the battle to win Senate confirmation of his nominee.

In effect, the president must choose to be bold or play it safe.

Merrick B. Garland, 58, an appeals court judge here, is well liked by elite legal advocates and is widely considered the safest choice if Mr. Obama wants to avoid a confrontation with the minority party. A former federal prosecutor who worked on the Oklahoma City bombings, he is well-known in Washington’s legal-political community, where some view him as a kind of Democratic version of Chief Justice John G. Roberts Jr.

Elena Kagan, 49, is solicitor general but has never been a judge and does not have a lengthy trail of scholarly writings, so her views are less well documented. But as the dean of Harvard Law School, she earned respect across ideological lines by bringing in several high-profile conservative professors, and she is a favorite among some in the extended Obama circle, who see her as smart and capable. Her relative youth means she could shape the court for decades to come.

Diane P. Wood, 59, a federal appeals court judge in Mr. Obama’s home city, Chicago, is seen as the most liberal of the three. She has been a progressive voice on a court that is home to several heavyweight conservative intellectuals. As a divorced mother of three, she brings the kind of real-life experience that Mr. Obama considers important. But her strong support for abortion rights would provoke a confrontation with conservatives. On Friday, the anti-abortion group Americans United for Life warned that a Wood nomination “would return the abortion wars to the Supreme Court.”

In making his selection, Mr. Obama confronts a vastly altered political landscape from the one he faced just 11 months ago, when he nominated Sonia Sotomayor to fill the seat left vacant by the retirement of Justice David H. Souter.

With the election of Senator Scott Brown, Republican of Massachusetts, Democrats can no longer hold off a Republican filibuster. And while Democrats are emboldened by the health care vote, the passage of the legislation — which is already facing legal challenges from Republicans who say it is unconstitutional — has left the Senate more polarized than ever and created a climate in which the courts could easily become an election issue.

For the court, Justice Stevens’s departure will be the end of an era. He is the longest-serving justice by more than a decade, and he is the last remaining justice to have served in World War II. (He joined the Navy, where he served as a cryptographer, the day before Pearl Harbor was attacked.) His leaving will not, however, change the composition of the court; although he was appointed in 1975 by President Gerald R. Ford, a Republican, he has become one of its most reliably liberal members during his nearly 35-year tenure, as the court drifted ever rightward.

Still, for Mr. Obama, who taught constitutional law at the University of Chicago (where he was a colleague of Judge Wood), the vacancy is an unmistakable chance to put his stamp on the direction the court takes for the next several decades. Mr. Obama is already engaged in an unusual public confrontation with the court over its recent decision in the Citizens United case, which lifted strict limits on corporate spending in elections. On Friday, during a brief appearance in the Rose Garden, he made clear that the case was very much on his mind.

He vowed to “move quickly” in announcing a nominee. Senior advisers said they expected a decision within the next several weeks. The president said he would look for a candidate who possessed what he described as qualities similar to that of Justice Stevens: “an independent mind, a record of excellence and integrity, a fierce dedication to the rule of law and a keen understanding of how the law affects the daily lives of the American people.”

And, in what legal scholars took as a clear swipe at the Citizens United decision (for which Justice Stevens wrote the dissent), the president said he would look for a justice who “knows that in a democracy, powerful interests must not be allowed to drown out the voices of ordinary citizens.”

The White House already has a Supreme Court nomination team in place, with the selection process run by the new White House counsel, Robert F. Bauer, and overseen by Rahm Emanuel, the chief of staff. Once a nominee is picked, Mr. Bauer’s wife, Anita Dunn, who is Mr. Obama’s former communications director, will coordinate with advocacy groups. Vice President Joseph R. Biden Jr., who was chairman of the Senate Judiciary Committee during some of its most contentious confirmation fights, is also likely to play a crucial role.

On Capitol Hill, Senator Patrick J. Leahy, the Vermont Democrat and the current chairman of the Judiciary Committee, said in an interview that Justice Stevens told him privately several weeks ago of his intentions. Mr. Leahy said he had had “long conversations” with the president and wanted a vote before the August recess so that a new justice could be installed by the start of the fall term.

“When I was the most junior Democrat in the Senate, I voted for John Paul Stevens,” Mr. Leahy said. “He was a Republican nominated by a Republican president who was going to be up for election, and we voted for him, and proudly.”

That kind of bipartisanship is highly unlikely this time. While both sides agree that Republicans are unlikely to use a filibuster to block a Supreme Court nominee, conservatives will at the very least use the debate to make the case for Republican candidates. They say they will calibrate their fight to how liberal they perceive Mr. Obama’s choice to be.

“If it’s someone like Merrick Garland, I don’t think there’s going to be a big fight,” said Curt Levey of the Committee for Justice, a conservative advocacy group. But Mr. Levey said a more liberal nominee, like Judge Wood, would “be a field day for the conservative groups.”

But leaders of liberal groups, like Nan Aron of the Alliance for Justice, are suspicious of conservative assurances that a more centrist nominee would face little opposition. They note that Justice Sotomayor was perceived by many on the left as far more centrist than they would have preferred, and yet Republicans portrayed her as a “judicial activist,” and 31 voted against her.

“No matter who he sends up,” Ms. Aron said, “I think Republicans are loaded for bear and will oppose.”

Democrats were divided Friday over whether Mr. Obama would pick a fight with Republicans or shrink from one. But Walter E. Dellinger III, who was acting solicitor general under President Bill Clinton, predicted passion, as much as politics, would play a role in Mr. Obama’s decision.

“I think that in choosing a Supreme Court justice,” Mr. Dellinger said, “the president is less likely to compromise and more likely to go with his heart than on any other matter.”

HORSE CREEK, W.Va. — As Janice Quarles waited for the phone to ring with news that her husband’s body had been pulled from the Upper Big Branch mine, she vowed — much as so many West Virginia mothers have before her — that her son, Trevor, 11, would never follow his father into the mines.

“There just ain’t no way,” she said.

But minutes later, concern for his safety was overwhelmed by another worry.

“If that’s the only kind of work there is around here, what choice does he have?” said Ms. Quarles, three days after losing her husband, Gary Wayne Quarles, in the worst American mining disaster in 25 years. “He’s got to make a living just like everybody else.”

Before stubbornly high levels of methane gas drove them back Thursday, rescuers had come within 500 feet of where the bodies of one group of miners may lie, with the authorities hoping that they would be able to restart the search Thursday night.

As devastating as it has been to this mountain community, the explosion that killed at least 25 miners on Monday has done little to alter the steel-toed blend of pride, resignation and economics that defines a coal miner’s life. Even as the rescue and recovery effort continued, workers at nearby mines day and night boarded the elevators that carry them miles into the earth.

Mining, unlike the low-wage jobs that predominate here, can provide a worker who is barely 20 years old with a home, a nice truck and a savings account.

“That’s the way it is around here,” Ms. Quarles said. “How many people can graduate high school today and tomorrow make $70,000 a year?”

Unlike in many households, where financial security brings peace of mind, in mining families the two are permanently at odds. Stephanie Pennington, for instance, is quick to acknowledge that her family lives well, with a three-bedroom home and a 2007 Dodge Durango, its rear window studded with decals of a pick and shovel, a crawling man with a headlamp, and the legend “WV Coal Miner’s Wife.”

But each night when her husband, Robert Shawn Pennington, leaves for the hoot-owl shift at the ICG Beckley coal mine here, she gathers her three children to pray. “I don’t sleep until I hear that key in the door every morning,” Ms. Pennington, 29, said. For her family, the anxiety spans the generations. Mr. Pennington’s father was crushed to death in the old Beckley mine while his mother was six weeks pregnant with him.

Here along the mountain roads, punctuated by hand-lettered signs advertising tiny churches or live lizards for sale, mining has enabled Thomas Dulin, 22, and his wife, Amanda, to buy an eight-acre farm and two donkeys, Chocolate and Chip.

Mr. Dulin, whose father is a federal mine inspector, was in college studying to be a teacher when he realized that he could make three times as much working as a miner.

In Raleigh County, where the Upper Big Branch mine is located, underground miners make an average of $1,476 a week, or more than twice the average income in the county.

Though Mr. Dulin came from a mining family, he had never been in a mine shaft before he decided to leave college. Now that he has spent time underground, he said, he realizes that money is not everything.

“I understand now why my parents didn’t want me to go in the mines,” he said. “Truly your health is very important, and I can see that now, and a lot of the older people in my family who spent 30, 40 years in the mine, I can see the toll it’s taken on them.”

Injuries are not the only danger; many develop respiratory ailments like asthma, silicosis and black lung.

Mr. Dulin said he would probably go back to college eventually, but to study in a coal-related field. In the meantime, he said, mining is an adventure-filled job, different on every shift. The crews are fraternities whose members watch out for one another even as they tease and play pranks, like greasing the controls of a piece of machinery when the operator is not looking.

Joking aside, a certain amount of rationalization is required before one can spend each day embedded in a mountain of rock, chipping away at it from the inside. Accidents can happen on any job, some miners say. Others say their lives are in God’s hands. Still others simply push thoughts of danger to the back of their mind.

“I try not to let it get to me in any way,” said James Songer, 21, whose face on Wednesday morning was still blackened with coal dust from the night shift. “Try not to think about it. Say a prayer before I go in.”

James Griffith, 57, whose brother, Bob, died in the explosion this week, said he had left mining for 18 years but returned when his wife needed health insurance. He said he would continue mining until he could no longer work.

“It’s kind of like if your dad was a butcher and he cuts his hand off,” he said. “Your mother’s not going to say, ‘I wish you’d stop being a butcher.’ It’s your family business. Unless you want to work at McDonald’s or somewhere.”

Stephen Franck, a miner for ICG, has other career options: he is a master plumber with a college degree. But he chooses to mine out of love for the job, he said. Mr. Franck, 30, said he felt for the men who died in the Upper Branch mine, but added: “I’m a coal miner. This is what happens.”

His mother, Edna Asbury, said she would give anything to see him change jobs.

“I wake up in the middle of the night and my mind automatically goes into a prayer for God to be with him,” Ms. Asbury said. “I told him this morning, ‘You’re going to have to start letting me hear from you every morning to know that you’re safe.’ He said: ‘Mom, you know this was bound to happen. It was their time to go, and they just all happened to be in a mining accident together.’ ”

The Upper Big Branch explosion has revived these types of arguments, but it has not altered the stalemate in which they usually end: if a miner quits, where will he find a comparable salary?

Such friction can begin even before a worker chooses to go underground. Evan Hash, 22, makes about $50,000 a year as a surface miner, a less risky and lower-paying job than deep mining. But with the birth of his first child last month, Mr. Hash is eager to take the classes required to go “down under.” He would make, he said, $1,200 more each month.

“My wife didn’t want me to,” he said as he contemplated second-hand mining uniforms for sale at an intersection outside of Eccles, W.Va. “I just got her talked into it.”

But his wife, Leona, 22, did not consider herself convinced. “He’s not going to go underground,” she said firmly, rocking the baby at a brisk tempo. “By the time he gets ready to go to school, he’ll be talked out of it.”

MONTCOAL, W.Va. — As rescue workers waited anxiously on Wednesday to re-enter the Upper Big Branch mine where at least 25 people were killed in a deadly blast this week, federal officials said two safety citations were made against the mine’s operator on the day of the explosion.

According to newly released records from the Mine Safety and Health Administration, one of the citations issued Monday against the operator, the Massey Energy Company, was for failing to properly insulate and seal spliced electrical cables. That citation was for a problem outside the blast area and the error was fixed immediately, federal mine safety officials said.

The other citation was for failing to keep maps of above-ground escape routes current. It was not immediately clear if federal inspectors were at the mine before the blast, or if the citations were issued for conditions they discovered after responding to the explosion.

At the time of the explosion on Monday, Kevin Stricklin, an administrator at the mine safety agency, was waiting at the airport in nearby Charleston, W.Va., on his way from Washington to a Massey mine in Kentucky. An agency spokesman said Mr. Stricklin was traveling to discuss various violations at the Kentucky mine. Mr. Stricklin quickly canceled his plans to visit the other Massey site and instead headed to the Upper Big Branch.

On Jan. 7, federal regulators issued two citations against the mine because the intake system that was supposed to pull clean air inside was moving air in the wrong direction. Similar problems were also noted by the mine safety agency after a 2006 fire at a Massey mine in Logan County, W.Va., killed two miners.

After that fire, the Aracoma Coal Company, a subsidiary of Massey, agreed to pay $4.2 million in criminal fines and civil penalties and to plead guilty to several safety violations. Over the years, Massey has accumulated a long record of violations and fines for its coal mining operations.

Massey representatives did not respond to multiple requests for comment.

Federal mining regulators said Wednesday that they had assembled a team to investigate the mining accident and that they hoped work would begin soon.

While local families clung to slim hope that survivors might soon be found, mining officials said more ventilation was needed before a search could continue. Workers continued drilling holes into the mine to help air out the methane and carbon monoxide gases that have accumulated, and a morning effort to contact the miners by beating on pipes met with no response. Thirty-one miners were in the area during a shift change when the explosion rocked the mine.

“We’re in a full rescue operation now, then we’ll go into recovery,” Gov. Joe Manchin III of West Virginia said at a news conference on Wednesday morning.

At the mine, families convened at an open warehouse on the Massey property, where local residents delivered food and condolences.

Because of the hilly terrain, cellular telephone reception is weak to nonexistent near the mine. As they waited for news, relatives of miners lined up at one of the few landline phones available near the site to call home and update loved ones.

Once workers re-enter the mine, it will probably take two to three hours to reach the area where the missing miners are believed to be, state officials said, adding that it was highly unlikely that survivors would be found.

Governor Manchin said he was concerned about reports of several recent work stoppages because of high methane levels in the mine before the explosion. The mine is supposed to be outfitted with air-quality sensors that shut machines off when methane levels grow too high.

“Why didn’t it happen this time?” Mr. Manchin asked, adding that he was eager to find out. “Why didn’t sensors go off?”

After their initial ventures into the mine, rescue workers said the explosion appeared to have occurred in its active section, not in the abandoned, sealed-off areas. Dennis O’Dell, a safety official with the United Mine Workers of America, said if that were true, it would indicate that the mine not only had methane problems, but also probably had dangerous levels of coal dust in the air.

Lawmakers in West Virginia and Washington said they planned to hold hearings to review what went wrong and what, if anything needed to be done to improve safety regulations.

In 2006, Congress conducted the biggest overhaul in federal mining regulations in three decades. Under the new federal regulations, mine operators are required to add emergency breathing devices and airtight rescue chambers to help miners escape explosions and fires. Companies were ordered to report serious accidents more quickly and to add more mine rescue teams.

Investigators will probably want to see whether the mine operator was in compliance with the requirement to have new communications and tracking gear to help miners reach people above ground and help rescuers locate missing workers.

Mr. Stricklin, of the mine agency, said it was not entirely clear whether the mine was in compliance. It had an approved tracking and communication plan in compliance with the federal law, but tracking equipment was not in place in the section of the mine where the missing miners are believed to be, he said.

Federal mining data indicates that only one in 10 underground mines nationwide have met the law’s requirements.

WASHINGTON

I’m a Catholic woman who makes a living being adversarial. We have a pope who has instructed Catholic women not to be adversarial.

It’s a conundrum.

I’ve been wondering, given the vitriolic reaction of the New York archbishop to my column defending nuns and the dismissive reaction of the Vatican to my column denouncing the church’s response to the pedophilia scandal, if they are able to take a woman’s voice seriously. Some, like Bill Donohue of the Catholic League, seem to think women are trying to undermine the church because of abortion and women’s ordination.

I thought they might respond better to a male Dowd.

My brother Kevin is conservative and devout — his hobby is collecting crèches — and has raised three good Catholic sons. When I asked him to share his thoughts on the scandal, I learned, shockingly, that we agreed on some things. He wrote the following:

“In pedophilia, the church has unleashed upon itself a plague that threatens its very future, and yet it remains in a curious state of denial. The church I grew up in was black and white, no grays. That’s why my father, an Irish immigrant, liked it so much. The chaplain of the Police and Fire departments told me once ‘Your father was a fierce Catholic, very fierce.’

My brothers and I were sleepily at his side for the monthly 8 a.m. Holy Name Mass and the guarding of the Eucharist in the middle of the night during the 40-hour ritual at Easter. Once during a record snowstorm in 1958, we were marched single-file to church for Mass only to find out the priests next door couldn’t get out of the rectory.

The priest was always a revered figure, the embodiment of Christ changing water into wine. (Older parishioners took it literally.) The altar boys would drink the dregs.

When I was in the 7th grade, one of the new priests took four of us to the drive-in restaurant and suggested a game of ‘pink belly’ on the way back; we pulled up a boy’s shirt and slapped his belly until it was pink. When the new priest joined in, it seemed like more groping than slapping. But we thought it was inadvertent. And my parents never would have believed a priest did anything inappropriate anyway. A boy in my class told me much later that the same priest climbed into bed with him in 1958 at a rectory sleepover, but my friend threw him to the floor. The priest protested he was sleepwalking. Three days later, the archbishop sent the priest to a rehab place in New Mexico; he ended up as a Notre Dame professor.

Vatican II made me wince. The church declared casual Friday. All the once-rigid rules left to the whim of the flock. The Mass was said in English (rendering useless my carefully learned Latin prayers). Holy days of obligation were optional. There were laypeople on the heretofore sacred ground of the altar — performing the sacraments and worse, handling the Host. The powerful symbolism of the priest turning the Host into the body of Christ cracked like an egg.

In his book, ‘Goodbye! Good Men,’ author Michael Rose writes that the liberalized rules set up a takeover of seminaries by homosexuals.

Vatican II liberalized rules but left the most outdated one: celibacy. That vow was put in place originally because the church did not want heirs making claims on money and land. But it ended up shrinking the priest pool and producing the wrong kind of candidates — drawing men confused about their sexuality who put our children in harm’s way.

The church is dying from a thousand cuts. Its cover-up has cost a fortune and been a betrayal worthy of Judas. The money spent came from social programs, Catholic schools and the poor. This should be a sin that cries to heaven for vengeance. I asked a friend of mine recently what he would do if his child was molested after the church knew. ‘I would probably kill someone,’ he replied.

We must reassess. Married priests and laypeople giving the sacraments are not going to destroy the church. Based on what we have seen the last 10 years, they would be a bargain. It is time to go back to the disciplines that the church was founded on and remind our seminaries and universities what they are. (Georgetown University agreeing to cover religious symbols on stage to get President Obama to speak was not exactly fierce.)

The storm within the church strikes at what every Catholic fears most. We take our religion on faith. How can we maintain that faith when our leaders are unworthy of it?”