On Thursday, at the Conservative Political Action Conference in Washington, Sen. John McCain stood before thousands of conservatives he has done his level best to anger and alienate for a decade -- to ask for their support.

And he made a not unconvincing case.

What he said essentially was this. We have fought each other in the past, and we have fought side by side. And I admit to having made my share of mistakes. But if we do not work together, we lose the presidency. And if we lose the presidency, your causes will be lost, as well as my last chance to be president.

But if you will work with me, many of the causes for which you have fought -- one more justice like Roberts and Alito, retention of the Bush tax cuts, further reductions in tax rates, a more secure border -- will be taken up as the causes of my presidency.

Moreover, my door will be open and your voices heard. And none of this will happen if Hillary or Barack Obama wins, which will happen if we do not join forces and fight together.

Bottom line: If we don't hang together, we all hang separately. If my end of the dinghy sinks, yours will not stay afloat. And if I lose, you get your pound of flesh, but we will both be out in the cold as a Democratic Congress and president undo what was right about the Bush presidency as well as what was wrong about the Bush presidency.

So it is your call.

McCain is no orator. But the speech had humility and humor -- and put the ball back squarely in the court of the conservatives. For John McCain had just taken the first step toward a rapprochement with the right, by asking for an armistice and offering an alliance.

In 1964, as an even more acrimonious battle for the GOP ended at the Cow Palace in San Francisco, where the right hooted and booed Nelson Rockefeller, another Arizonan was far less compromising than John McCain. Barry Goldwater told that convention of conservatives that had just nominated him: "Anyone who joins us in all sincerity, we welcome. Those who do not care for our cause, we don't expect to enter our ranks in any case."

Conservatives now have a decision to make, though months before they have to make it. That decision: Is it better to cede the White House to the Democrats than have McCain become president of the United States and leader of the Republican Party and the nation?

Many have already made that decision: Better, they argue, to lose to Hillary than win with McCain. Better to be principled than pragmatic. As John F. Kennedy once said, "Sometimes party loyalty asks too much."

If the issue were simply, "Does McCain deserve the support of conservatives?" the answer would be simple and emphatic: No. Indeed, John McCain has fully earned the repudiation he received in the Arizona primary, when Mitt Romney ran far ahead among conservatives.

However, there is a question other than whether McCain deserves the support of the right, and it is this: Would it better serve the causes in which conservatives believe to have McCain in the White House or to have Clinton there?

If Hillary or Obama wins, as Jimmy Carter beat Gerald Ford in 1976, there is, argue some conservatives, a chance for a restoration in 2012, just as happened in 1980 when Reagan ousted Carter, sweeping 44 states and bringing in the first Republican Senate in a quarter century. And we got the Reagan Decade.

But if Hillary or Obama wins, the likelihood is good that either would nominate the next two justices to the Supreme Court. And there is no doubt that any Clinton or Obama nominee will be in the mold of Ruth Bader Ginsberg, not Antonin Scalia, and the long battle for the Supreme Court will be lost irretrievably.

The most powerful case against McCain is that, put brutally, he is not to be trusted.

Many on the right believe that if he wins, he will have no further need of conservatives and will revert to the McCain of McCain-Feingold, McCain-Kennedy and McCain-Lieberman, the John McCain of the Gang of 14, who will never nominate justices like Sam Alito, because that would alienate his true constituency, the media, who are at his feet every time he undermines the conservative cause.

There is another consideration. McCain has said he will stay in Iraq another 100 years if necessary, that Russia should be thrown out of the G-8, that he will do whatever it takes to halt Iran's nuclear enrichment program. He has told us: "There's going to be other wars. ... I'm sorry to tell you, there's going to be other wars. We will never surrender, but there will be other wars."

John McCain seeks to be a war president. Indeed, it is the role of commander in chief of a nation at war that seems to commend itself most to John McCain. But is that good for America, let alone the right?