President Bush is keeping confidential his short list of possible nominees should one or more Supreme Court justices retire. But in conversations with former White House officials and others, the same names keep coming up. Brief biographies of 10 of them follow, very roughly in order of their prominence in the Supreme Court succession speculation game.

That game has intensified in recent weeks. One reason is the possibility that 80-year-old William Rehnquist’s serious case of thyroid cancer may spur him to retire as chief justice. Another is that President Bush’s re-election might prompt other aging justices to depart, whether because they want Bush to name their successors or because they can’t wait any longer for a Democratic president. Liberal John Paul Stevens is 84; moderate, swing-voting Sandra Day O’Connor is 74; liberal Ruth Bader Ginsburg is 71; and the others are 65 or over, excepting 56-year-old Clarence Thomas. Nobody has left the Court in more than a decade, the longest such period since the 1820s.

Liberal and conservative groups are feverishly rallying their troops and preparing their ammunition for the confirmation battles that they know will come sooner or later. Liberals vow total war against any Bush nominee who would tip the Court’s precarious ideological balance to the right. A conservative replacement for the conservative Rehnquist would not do that. But liberals would still mount a ferocious attack if the nominee were a provocative conservative. The liberals’ chances of winning would be slim, however, now that the Senate will have 55 Republicans in January.

A Rehnquist retirement would present Bush with two options: to pick someone outside the Court to become chief justice, as most presidents have done, or to pick one of the current associate justices — most likely conservative firebrand Antonin Scalia or O’Connor — to be chief while choosing someone else to be the new associate justice. Both nominees would be subject to Senate confirmation. One Washington lawyer who has been very widely touted as a possible Bush nominee to the Supreme Court, Miguel Estrada, has made it known that he is not interested in being considered. Estrada recently suffered tragedy when his wife died in her sleep.

Here’s the list.

John G. Roberts Jr., Washington, D.C., U.S. Court of Appeals for the District of Columbia Circuit, 49. A former clerk for Rehnquist, he served in the Reagan Justice Department and White House counsel’s office, became an appellate litigator, and then was the principal deputy solicitor general under the first President Bush. He has argued dozens of cases before the Supreme Court. Roberts was originally nominated for the D.C. Circuit in 1992 by Bush I, but Senate Democrats stalled his nomination until after the election. When he was renominated in 2001, Senate Democrats stalled again before confirming him in May 2003. Pluses: He is likable, greatly admired by other lawyers and judges, and seen by some as a moderate conservative. Minuses: Liberals suspect he may be quite conservative; his judicial experience has been brief.

J. Harvie Wilkinson III, Charlottesville, Va., U.S. Court of Appeals for the 4th Circuit, 60. He has been a law clerk for Justice Lewis F. Powell Jr., a law professor, a newspaper editor, and a deputy chief of the Reagan Justice Department’s Civil Rights Division. President Reagan appointed him to the 4th Circuit in 1984. Pluses: He has a first-rate legal mind and a courtly manner. Minuses: Some Democrats see him as a conservative activist, and some conservatives suspect he’s too moderate.

J. Michael Luttig, Alexandria, Va., U.S. Court of Appeals for the 4th Circuit, 50. He clerked for then-Judge Scalia and for Chief Justice Warren E. Burger, worked in the White House counsel’s office under Reagan, spent four years at a big law firm, and held important Justice Department positions before the first President Bush appointed him in 1991 to the 4th Circuit, which has become the most conservative of the 12 regional federal courts of appeals. Luttig’s judicial opinions are logical tours de force that thrill conservatives, scare liberals, and sometimes skewer colleagues — especially Wilkinson. Pluses: He has a potent intellect, an agreeable personality, and strong conservative support. Minuses: Liberals would go to war to stop him.

Samuel A. Alito Jr., Newark, N.J., U.S. Court of Appeals for the 3rd Circuit, 54. He was a federal prosecutor, assistant solicitor general, deputy assistant attorney general, and U.S. attorney for New Jersey before President George H.W. Bush appointed him to the 3rd Circuit in 1990. Pluses: His conservative jurisprudence is admired by the Bush camp. Minuses: Liberals, who call him "Scalito," would fight.

Alberto R. Gonzales, Washington, D.C., Bush’s White House counsel and nominee to be attorney general, 49. A child of uneducated Mexican-American immigrants, he grew up in a Texas house without a phone or hot water. Gonzales joined the Air Force after high school and ended up graduating from Harvard Law School. He was hired away from a big Houston law firm in 1995 to become legal counsel to then-Gov. Bush, who appointed him secretary of state in 1997; put him on the Texas Supreme Court in 1999; and made him White House counsel in 2001. He is one of the president’s most trusted advisers and a likely nominee for any vacancies later in Bush’s term. But Bush may want to keep him as attorney general for now. Pluses: He is Hispanic; liberals see him as relatively moderate on social issues. Minuses: Conservatives say he’s too liberal, especially on affirmative action and abortion. Others see him as an undistinguished yes-man for a president who disdains constitutional liberties, and they especially deplore his role in the now-disavowed legal memos suggesting that the president can order the torture of suspected terrorists.

Larry D. Thompson, Purchase, N.Y., a senior vice president of PepsiCo, 59. Before serving two years as Bush’s first deputy attorney general, he had been U.S. attorney for Georgia and a litigator with a large firm in Atlanta. Thompson has been a critic of racial preferences, although less passionate than his close friend, Justice Clarence Thomas. Pluses: He is African-American, is likable, and has impressed people ranging from Bush to some Senate Democrats. His paper trail might be hard for Democrats to attack. Minuses: Liberals suspect that he may share some of Thomas’s archconservative views.

Michael W. McConnell, Salt Lake City, U.S. Court of Appeals for the 10th Circuit, 49. After serving as a law clerk to Justice William Brennan Jr., he worked in the solicitor general’s office and then as a law professor, becoming one of the most widely respected conservative legal scholars. McConnell’s nuanced views focus on the First Amendment’s religion clauses. He personally opposes abortion and is an eloquent critic of some liberal decisions, including Roe v. Wade. Nominated for his current seat in 2001, McConnell was confirmed 14 months later, after vowing faithfully to follow the precedents he has criticized and getting a boost from admiring liberal academics. Pluses: Stellar intellectual credentials; support in legal academy. Minuses: Liberal groups would go all-out to stop him; conservatives worry that his views on many issues are unknown.

Theodore B. Olson, Washington, D.C., partner, Gibson, Dunn & Crutcher, 64. Olson is the go-to appellate litigator for conservatives. He headed the Justice Department’s elite Office of Legal Counsel during Reagan’s first term and then returned to Gibson, Dunn to build a Supreme Court and appellate practice. Olson represented George W. Bush in the Supreme Court litigation that effectively made Bush president four years ago. Bush then chose Olson as his solicitor general, and the Senate confirmed him by 51-47 after a tough battle. His wife — lawyer and conservative television pundit Barbara Olson — died on the airliner that terrorists crashed into the Pentagon on September 11, 2001. Olson stayed on as solicitor general until last summer, when he returned to Gibson, Dunn. Pluses: He is a hero to conservatives and is unusually likable. Minuses: Liberals say he would be a conservative judicial activist, and they are still bitter about Bush v. Gore.

Emilio M. Garza, San Antonio, U.S. Court of Appeals for the 5th Circuit, 57. He was appointed by Reagan to the U.S. District Court and elevated by the first President Bush in 1991 to the 5th Circuit. He is a former marine, corporate litigator, and Texas state judge Pluses: He is Mexican-American and is respected among conservatives. Minuses: Liberals would fight him because he has said that Roe v. Wade was judicial legislation and should be overruled.

Janice Rogers Brown, Sacramento, Calif., state Supreme Court, 55. She is one of the Bush judicial nominees who has been stalled by a Democratic filibuster. The daughter of an Alabama sharecropper, Brown put herself through college and UCLA Law School, worked in the state attorney general’s office, and became Republican Gov. Pete Wilson’s legal affairs secretary in 1991. Wilson put her on an intermediate appellate court in 1995 and made her the California Supreme Court’s first black female justice in 1996. She is a forceful, acerbic libertarian conservative who has denounced the Supreme Court decisions that upheld New Deal programs, in 1937 and thereafter, as a "disaster" marking "the triumph of our socialist revolution." Pluses: She is African-American and has a powerful, independent intellect admired by many conservatives. Minuses: Her strong rhetoric offends some colleagues; she may be a more radical conservative than any current justice.