Employing essentially the same game plan they used to win referendums against same-sex marriage in 11 states last November, evangelical Christian groups said they plan to run a multimillion-dollar church-centered campaign to rouse support for a thoroughly conservative successor to Supreme Court Justice Sandra Day O'Connor.

Conservative religious leaders said the campaign will target 20,000 pastors and congregations using Christian talk radio, satellite television broadcasts, direct-mail advertising and aggressive grass-roots organizing.

"This is the moment that social conservatives have been awaiting for more than a decade -- a real chance to change the philosophical balance of the Supreme Court" and reverse the direction of its rulings on abortion, school prayer, sodomy and religious displays on public property, said Tony Perkins, president of the Family Research Council.

A year ago, Perkins predicted that petition drives for state constitutional amendments to ban same-sex marriage would have an enduring political impact because they would forge local Christian activists across the nation into "hard-wired" networks with names, addresses and telephone numbers of supporters.

That is exactly what happened, he said in an interview Saturday.

"I've heard people say the fiscal conservatives, the business interests, are hoping the social conservatives will be quiet this time. If we're quiet, they won't be successful, because we're the ones who can gear up people around the country. The engine has been idling since the election, and all we have to do is rev it up again," he said.

The revving began within hours of O'Connor's surprise resignation Friday morning, when about 50 members of the Arlington Group, a coalition of evangelical activists that first coalesced against same-sex marriage, held a conference call to discuss strategy for the judicial nomination battle.

Unlike in the group's weekly teleconferences during last year's presidential campaign, however, there was no one from the White House on the line, several participants said.

Connie Mackey, the Family Research Council's vice president for government affairs, said that was because "there is no need to coordinate with the White House at this stage," before President Bush names his choice to succeed O'Connor.

But it was also because the initial target of pressure from the Christian groups is, in fact, the White House: They want to hold Bush to his campaign promise to nominate someone like Justices Clarence Thomas and Antonin Scalia. Publicly, they expressed no doubt that Bush would do so.

"I've known this president since 1988, and it's been my experience you don't need to remind him of the promises he's made," said the Rev. Richard Land, head of the ethics and public policy commission of the Southern Baptist Convention.

At the same time, they made it clear that they would not automatically throw their weight behind anyone the president names. Asked, for example, whether the Family Research Council would support Attorney General Alberto R. Gonzales for a seat on the high court, Perkins replied acidly: "Our position on Attorney General Gonzales is, he holds great promise as an attorney general."

Many leaders on the Christian right were bitterly disappointed by the rulings of O'Connor, who had been a Republican legislator in Arizona before her appointment to the court by President Ronald Reagan. "More often than not, she voted with the liberals on the important social issues we care about," said Jan LaRue, chief counsel for Concerned Women for America, which calls itself the nation's largest Christian women's group.

Yet LaRue and other evangelical leaders said there was no elation over O'Connor's departure in their teleconference calls or in the map-lined third-floor "war room" of the Family Research Council's G Street headquarters.

"We'll save the joy and elation until after we win," Land said. "We all know this is going to be painful, it's going to be big, it's going to be divisive, it's going to be ugly."

Federal tax laws prohibit tax-exempt religious organizations from endorsing or opposing candidates for office. But they do not bar churches from addressing political issues, such as the definition of marriage or who belongs on the Supreme Court, Land said.

Assuming that Bush nominates someone to their liking, Perkins said the Family Research Council and allied groups, such as James Dobson's Focus on the Family, "will mobilize 20,000 churches" to press the Senate for confirmation. He said they will work largely through pastors, noting that the Family Research Council has held annual conferences in recent years for hundreds of pastors from more than 40 states.

According to participants, the Arlington Group's initial strategy sessions have focused on the timeline for the confirmation battle -- including the possibility that the Senate will forgo its August break -- and how best to frame the debate. So far, the main talking points among religious conservatives are: "in the mold of Thomas and Scalia," "no more Borking" and "Roe v. Wade."

By a justice "in the mold of Thomas and Scalia," Land said, social conservatives mean they want someone who is both a "strict constructionist" and adheres to the "original intent" of the framers of the Constitution.

By "no more Borking," they mean they are determined to avoid a replay of the Senate's 1987 defeat of the nomination of Judge Robert H. Bork. Concerned Women for America is distributing a tape of Bork speaking about the savagery of his opponents; LaRue said religious conservatives "will be prepared this time."

In the possibility of overturning Roe v. Wade, the 1973 decision declaring a woman's constitutional right to choose an abortion, conservative leaders see an issue that unites many of their followers but that could alarm other Americans. Thus, some are quick to explain that achieving this prized goal would have a limited immediate impact.

"I've heard the other side talk about it as the end of the world. But really, it will just be a different process," said Cathy Cleaver Ruse, a former spokeswoman on life issues for the U.S. Conference of Catholic Bishops who has been hired by the Family Research Council for the nomination battle. "When Roe v. Wade is overturned, we start a whole new process in American democratic life, tackling the issue of abortion largely through the states rather than through the courts."

The Family Research Council's Tony Perkins hopes to alter the court's "philosophical balance."