Rudy Giuliani's candidacy for the Republican presidential nomination presents conservative Republicans with a real conundrum. Should they support the candidate who will put up the best fight, though he (or she) disagrees with them on virtually all of the social issues? Or should they insist on a candidate who truly represents conservative values, even if they suspect he might be a degree or two less combative against (say) Hillary Clinton in the campaign?

My own brooding on this question is decisively affected by my conviction that 2008 is going to be a Democratic year. I believe the Democrats are very likely to win the presidency and strengthen their hold on both Houses of Congress. Barring a dramatic turnaround in the next 12 months, the Iraq war is bound to be a major negative factor in the Republican equation, even if (as seems to be the case) the situation is improving a bit. The economy doesn't appear to be doing anything that voters regard as redounding to the Republicans' credit. Above all, the Republicans have been in office for a reasonable length of time, and there is an understandable inclination on the part of the electorate to think it's the other guys' turn.

Of course, 2008 won't be the end of the world. There will be other elections, and the Republicans will win a fair share of them. There might even be some dramatic shift in the probabilities in 2008: If, for example, a major terrorist attack on the United States occurred in September or October, pushing everything but security out of the voters' minds. But I urge you not to be deluded into thinking that America just can't stand Hillary, or that political cycles can be disregarded. Barring the unimaginable, 2008 is going to be a Democratic year, and Hillary may well be back in the White House, this time as Madam President.

If so, what good will it do conservative Republicans to nominate a candidate who can undeniably put up a dogged fight, but will abandon, in the process, 70 percent of the principles that conservatives believe are worth fighting for? Let's concede that, on the Iraq war, and to the extent that we know them (an important reservation) on foreign issues generally, Giuliani is in synch with conservative positions. But on Dec. 2, 1999, he asserted, "I'm pro-choice, I'm pro-gay rights," and when asked whether he would support a ban on partial-birth abortion, he told CNN's "Inside Politics": "No, I have not supported that, and I don't see my position on that changing."

Gun control? On March 21, 2000, he told the Boston Globe: "Anyone wanting to own a gun should have to pass a written exam that shows that they know how to use a gun ..."

Immigration? In November 2006, he supported the Senate plan for guest workers, with a path to citizenship -- a plan that was stopped dead in its tracks by a subsequent tidal wave of public opposition.

Now, it's perfectly true that Giuliani's positions on these and practically all other social issues are matched -- and indeed outmatched -- by those of any likely Democratic contender. So it's fair to argue that, however unsatisfactory Giuliani might be as president, "he wouldn't be as bad as Hillary!"

But if it is true that the Democrats are overwhelmingly likely to win in 2008, then Giuliani won't have the chance to be a better president than Hillary. He will simply be the image that the Republican Party chooses to offer the public next year: a tough New York politician who knows how to wage a good fight, but differs with his conservative fellow Republicans on just about every social issue.

I cannot believe the American people will respect the Republican Party more if it is willing to abandon some of its core principles, believing that they are transiently unpopular. Far better to lose, if lose we must, with a Mitt Romney or a Fred Thompson than with a Giuliani. For with Giuliani, we will not only lose the election but the core values that represent the only reason to hope for victory.