The White House gathered key political operatives at a strategy meeting Friday to prepare for a possible Supreme Court vacancy that officials believe could occur this week, leading to the first high court confirmation battle in a decade, according to Republicans informed about the session.

The meeting, hosted by White House Chief of Staff Andrew H. Card Jr., his deputy Karl Rove and counsel Harriet Miers, was called to ensure that President Bush's supporters are ready for the high-stakes, high-intensity, high-dollar campaign that would follow a nomination. But some participants later told associates that they were not sure if any justice would retire.

Much of Washington has been anticipating word from Chief Justice William H. Rehnquist on whether he will retire after 19 years as the nation's top judge. Rehnquist, 80, has thyroid cancer, and many officials, jurists and activists believe he will step down after the court's current term ends today. From the White House and Capitol Hill to lobbying groups, both sides spent the weekend mobilizing on that assumption.

Rehnquist's resignation would presage a struggle of enormous proportions between the two parties and their ideological allies -- one that would likely eclipse the recent Senate showdown over lower-court appointments and that could overshadow the rest of Bush's domestic agenda for months.

By most accounts, it would rival a presidential campaign, complete with extensive television advertising, mass e-mails, special Internet sites, opposition research, public rallies and news conferences. Both Democrats and Republicans have been raising money for this moment for years. The president's allies have promised to bankroll an $18 million public relations blitz, and administration opponents have set up a war room and enlisted veterans of the campaigns of Bill Clinton and Al Gore to devise strategy.

"This has been such a huge political spectacle that this is not your run-of-the-mill confirmation hearing," said Kenneth M. Duberstein, a former Reagan White House chief of staff who shepherded two high court appointments through the Senate for President George H.W. Bush. "This is a fundamental decision about the future of the Supreme Court. Everybody's eyes are peeled, and the far left and the far right are ready."

Since Clinton's 1994 appointment of Stephen G. Breyer, no justice has left the court, the longest period of stability since the 1820s. Although Supreme Court nominations at times have polarized Washington and much of the nation -- most notably those of Robert H. Bork and Clarence Thomas -- none has taken place in an era so saturated by 24-hour cable news, e-mail, bloggers, talk radio and seemingly bottomless financial resources.

"The interest groups have sizable war chests," said David Alistair Yalof, a University of Connecticut professor and author of "Pursuit of Justices," a 1999 book on Supreme Court nominations. "It's been so long that they've been saving their ammunition, and they're obviously going to use it, especially if it's a chief justice. You have interest groups that are chomping at the bit."

If Bush nominates a like-minded conservative, Rehnquist's retirement would not put the philosophical balance of the court in play. But it would still generate fireworks because the court is closely divided on many key issues, particularly the Roe v. Wade decision establishing a woman's right to an abortion. If Bush picks someone around age 50, as advisers expect, the next chief justice could run the court for three decades.

Conservatives want to ensure that Bush remains faithful in his selection rather than choosing a moderate who might be easily confirmed by appealing to Senate Democrats. The situation would become even more heated if another justice retires, particularly the centrist-conservative Sandra Day O'Connor, 75, or the liberal John Paul Stevens, 85 -- a prospect most, but not all, insiders discount.

The White House has been preparing for a nomination for four years and almost certainly would be ready to announce a choice right away. Outside advisers believe the front-runners are U.S. Court of Appeals judges J. Michael Luttig of the 4th Circuit and John G. Roberts of the D.C. Circuit, both considered strong conservatives. Bush might also prevail upon his reluctant friend, Attorney General Alberto R. Gonzales, who would be the first Hispanic justice but is seen by some conservatives as unreliable on issues such as abortion and affirmative action.

Other possible candidates include Appeals Judges Samuel A. Alito Jr. of the 3rd Circuit, Michael W. McConnell of the 10th Circuit, Emilio M. Garza of the 5th Circuit and J. Harvie Wilkinson III of the 4th Circuit. White House advisers doubt that Bush would elevate a current member of the Supreme Court to chief justice.

"Obviously, if there is a vacancy, we are prepared for that scenario, like any White House," press secretary Scott McClellan told a briefing Thursday without elaborating. "We have made preparations to be ready in case someone does leave the Supreme Court. At this point, no one has."

A court nomination would further complicate Bush's efforts to push through his stalled domestic program, including changes in Social Security, liberalized immigration rules, a Central American free-trade pact, energy legislation and the nomination of John R. Bolton as U.N. ambassador.

"It'll be the big story," Republican strategist Charles Black said of a court nomination. How big, he added, depends on Bush's choice and the Democrats' response.

A senior White House official put it this way: "It paralyzes everything else." The official insisted on anonymity because no vacancy has been announced.

Whether it will happen remained mostly guesswork yesterday. Rehnquist has stayed publicly mum. Although some people who saw him at a reunion of former clerks were struck by how his health has deteriorated, congressional leaders who saw him at a recent lunch said the chief justice seemed stronger.

If Rehnquist has made a decision, it is unclear whether he has told the White House. Rove and others who participated in the strategy session on Friday characterized it as a precaution, according to Republicans, rather than confirmation that an opening is certain.

The president's public schedule for the week also seemed to send mixed signals. The White House announced that Bush will travel to North Carolina tomorrow for a nationally televised speech on Iraq, suggesting he does not expect to be introducing a nominee the day after the Supreme Court term ends. At the same time, the White House kept Wednesday's schedule clear, perhaps reserving it to announce a nomination after letting Rehnquist enjoy his day in the sun if he were to retire today.

"It really is like Kremlinology or the picking of a pope," said Sean Rushton, executive director of the Committee for Justice, a group established to support Bush's judicial nominations. "Everyone's reading the smallest signals. We're acting as if it's going to happen. . . . A lot of people are working through the weekend to make sure they've got their ducks in a row."

Rushton said his group is updating biographies of prospective nominees, getting news releases ready, preparing e-mail lists and media contacts. Across town, his rivals at the liberal People for the American Way were doing much the same. Ralph G. Neas, the group's president, said it sent 1 million e-mail and regular mail messages last week, and has about two dozen draft news releases ready to issue, depending on what happens.

The group and its allies have set up a 2,500-square-foot war room with 40 work stations and 75 phone lines, and signed up Democratic heavyweights such as former Clinton White House press secretary Joe Lockhart and former Gore strategist Carter Eskew to run the effort. "It's a presidential campaign-caliber team," Neas said, as about 10 fellow workers gathered for meetings.

"It's certainly the conventional wisdom that something's going to happen and it's going to happen soon," he added. "But . . . the conventional wisdom can be wrong."

Speculation has intensified that Chief Justice William H. Rehnquist, 80, might retire soon.