President Bush has decided on a nominee to fill an upcoming Supreme Court vacancy and will announce his choice at 9 p.m. tonight, the White House said.

Bush will make the announcement in a nationally televised appearance in the East Room of the White House, presidential spokesman Scott McClellan told reporters.

The nomination of a replacement for Justice Sandra Day O'Connor, who announced July 1 that she would retire upon the confirmation of her successor, carries high stakes politically because justices are lifetime appointees and can leave their mark on major issues for decades.

With Chief Justice William H. Rehnquist determined to stay on the high court despite a battle with thyroid cancer, the retirement of O'Connor gives Bush his first chance to place someone on the Supreme Court. O'Connor, 75, was the first woman to be named to the court, and Bush lately has come under pressure -- from his wife, among others -- to appoint another woman to replace her.

One potential replacement whose name was bruited about today is Edith Brown Clement, a judge on the U.S. Court of Appeals for the 5th Circuit, based in New Orleans.

But while many Republican strategists anticipated that Bush would choose Clement, other observers cautioned against such speculation. In fact, several men remained in the mix of candidates whose names have surfaced in recent weeks.

Among them were Attorney General Alberto R. Gonzales, former deputy attorney general Larry Thompson and federal appeals court judges J. Michael Luttig, Emilio Garza and John G. Roberts.

Bush himself was noncommittal earlier in the day as he took questions from reporters after a meeting with visiting Australian Prime Minister John Howard.

Asked about replacing O'Connor with another woman and whether he has finished interviewing candidates, Bush said, "I have thought about a variety of people, people from different walks of life, some of whom I've known before, some of whom I had never met before." He added to laughter from reporters, "I'm trying to figure out what else I can say that I didn't say yesterday that sounds profound to you without actually answering your question." He concluded, "I'll let you know when I'm ready to tell you who it is."

He did not answer a subsequent question specifically about Clement.

Other leading female contenders for the nomination, according to GOP strategists, Edith Hollan Jones and Priscilla R. Owen, who sit with Clement on the U.S. Court of Appeals for the 5th Circuit; Janice Rogers Brown of the U.S. Court of Appeals for the D.C. Circuit; and Karen Williams of the 4th Circuit Court of Appeals.

Jones, admired by many conservatives as a "strict constructionist" in interpreting the Constitution, was the runner-up to David H. Souter when President George H.W. Bush made his first court appointment in 1990. She has expressed strong opposition to Roe v. Wade , the decision establishing a constitutional right to abortion.

Owen and Brown were just confirmed to the appellate bench, after long Democratic delays, as part of a May deal to end a partisan showdown over judicial filibusters. If Bush picks either of them, strategists said, the White House will argue that the Senate could hardly reject the nomination months after approving the same person for a lower-court post. But such a move would be seen as provocative by Democrats who reluctantly dropped their filibuster against those two.

The Senate minority leader, Sen. Harry M. Reid (D-Nev.), said today that he and other Democrats appreciate Bush's consultations with them on a nominee, but that whether those talks have been "beneficial" will depend on whom the president nominates.

"As to whether it's going to be a conflict and further animosity here in the Senate between parties depends on the president," Reid told reporters. "If this is a noncontroversial candidate, there's no reason that we can't use the August recess to have the Judiciary Committee members read the briefs," he added, referring to a judge's written opinions in court cases.

Reid said he saw no reason that hearings on such a nominee could not be held in early September, with a confirmation by Oct. 1 in time for the Supreme Court's next session.

The Senate's top Democrat also noted that all the talk about a Supreme Court nominee had pushed aside a growing controversy over the role of Karl Rove, the White House deputy chief of staff and Bush's top political strategist, in the leaking of a covert CIA agent's identity.

Reid said he was "very disappointed" in Bush's remark yesterday that he would fire any White House official who "committed a crime" in the case, a formulation that effectively raised the threshold for dismissals in the matter. Bush had previously said he would fire the person who leaked CIA agent Valerie Plame's identity. Although Rove, through his lawyer, has acknowledged speaking with a reporter about Plame, he has denied identifying her by name, and legal analysts have said it would be hard to prove he committed a crime.

"The American people really deserve better than this, better than a president changing the rules in the middle of the ball game," Reid said.

Sen. Mitch McConnell (R-Ky.), the majority whip, told reporters that the Senate owes the public "a respectful process during the committee hearings and the floor consideration" of a Supreme Court nominee. He said Bush went through "unprecedented" consultations before making his choice and that "a clear majority of the Senate was consulted during this process."

A Republican strategist with close ties to the White House said earlier in the day that "the signs are all pointing to Clement." But other sources were signaling later that she may not be the choice.

Clement, 57, served for 10 years on the U.S. District Court for the Eastern District of Louisiana before being elevated to the 5th Circuit Court of Appeals.

She was nominated to the District Court by President George H.W. Bush in October 1991 and promptly confirmed by the U.S. Senate. In 2001 she served as chief judge of the District Court.

Clement was born in Birmingham, Ala., and earned a bachelor's degree from the University of Alabama in 1969 and a law degree from the Tulane University School of Law in 1972.

After passing the bar, she was a law clerk for U.S. District Court Judge Herbert W. Christenberry in the Eastern District of Louisiana.

From 1975 until she became a judge in 1991, Clement worked in private practice in New Orleans, specializing in maritime law. She represented oil companies, insurance companies and the marine services industry in cases before federal courts.

She is a member of the Federalist Society, a conservative legal organization.

Clement has a reputation among lawyers as a no-nonsense judge who insists on professionalism in her courtroom and is strict about deadlines. While she is known as a judicial conservative, she also has been known to lean toward the defense in civil cases.