Republicans were stunned this week by news that prominent social conservative leaders are ready to abandon their winning coalition — virtually handing Democrats the White House — if Rudy Giuliani wins the GOP nomination.

These leaders must not lose their command focus on what’s at stake in this election. They may not get another chance to impact the Supreme Court in such a dramatic way for a long time.

Conservative voters must be prepared to support candidates who share their vision of a non-activist, constructionist Court, even if they disagree on some important issues. The alternative — another Clinton presidency — would be disastrous to their cause.

If social conservatives support a hopeless third party candidate, their dream of changing and then maintaining the Supreme Court will be lost. They must keep their eyes on the prize.

The Court has been remaking America since the 1960s, with liberal justices forcing their social agenda down our throats. The Court started inventing constitutional rights not found in the words of the Constitution, removing these issues from the democratic process.

This liberal social agenda did not come from any president. The Court created this problem; only the Court can fix it. The focus must be what sort of justices a president would appoint.

Abortion, same-sex marriage, racial preferences, and religious freedom are all ultimately decided by the Supreme Court.

We’re just one vote shy of undoing the damage. President Bush has appointed concrete judges to the federal bench, including two solid Supreme Court justices.

But, we are still one vote from the goal. Pro-life advocates make a terrible mistake if they think they’ve won. They have not. This is not a conservative Court; it is an evenly-split Court. This Court has four liberals, four conservatives, and one moderate.

That moderate, Justice Kennedy, has made it clear he will not overturn Roe v. Wade. He supports a constitutional right to homosexuality and will not roll back overreaching federal power. He also will not change the Supreme Court precedents driving expressions of faith from the public square.

The 5-4 cases conservatives won over the last year were barely won with narrow opinions, and they have lost more cases than they have won. Another conservative justice is needed.

And the next president will appoint at least two justices.

More than that, the next justices to retire are the most liberal. By early 2009, John Paul Stevens will be 89 years old and Ruth Bader Ginsburg, with a history of serious health problems, will be 76. Replacing either would fundamentally alter the ideological makeup of the Court.

Conservatives differ with Mr. Giuliani on social issues. He’s committed to balancing the budget, stopping pork-barrel spending, not raising taxes, fixing entitlements, growing the economy, enhancing national security, building our military, and fighting terrorism. Aside from social issues, that’s the entire conservative agenda.

And the social issues will be decided by the Supreme Court.

Mr. Giuliani — who was part of the Reagan Justice Department — repeatedly says what kind of justices he would appoint. He names Antonin Scalia and Sam Alito as examples of whom he would nominate. They’re exactly the sort of justices conservatives have fought for years to get on the Court.

And there are safeguards in place. Supreme Court confirmations are not what they used to be. Whole organizations focus on it. Everyone knows who’s on the short list. There’s no chance of another Souter, where a supposed conservative turns out to be a liberal. No one gets the benefit of the doubt. Remember Harriet Miers.

If social conservatives disagree with Mr. Giuliani they should work to beat him in the primaries. Why the allure of the quixotic “third party” rather than a real, principled primary fight? If the issues are life, marriage, and Second Amendment freedoms, and the objective is to win, a good bet seems to be Mike Huckabee. He is right on these issues. And, he has been highlighted by pundits on all sides as the one to watch for a breakthrough.

Several of the current Republican candidates could make strong and effective presidents. My point is that they’re all equal on what social conservatives should care about most — the direction of the Court.

Rather than hand the White House, and therefore the Supreme Court, to Hillary Clinton without a fight, social conservatives and evangelicals should make a hard, principled stand in Iowa, New Hampshire, Michigan, South Carolina, and Florida on behalf of their preferred candidate. If they are not successful, and Mr. Giuliani is the nominee, they should work hard for his victory while constantly reminding him of his intentions regarding judicial appointments.

And, Mr. Giuliani, if successful, has a responsibility to reach out and talk with social conservative leaders. He cannot go around the movement’s leadership. Millions rely on them to benchmark candidates. Ignoring them will cost Mr. Giuliani millions of votes and the White House.

If he is willing to dialogue, then conservative leaders need to engage him. Earl Warren, David Souter and others have surprised the Republican presidents who nominated them. With Mrs. Clinton, there will be no surprises.