Contrary to Peter's post below, I think the most prudent conservative course of action is to vote for Gingrich--for now. The problem is that conservatives have the choice between a dynamic right-wing Progressive with a flawed moral past, one temperamentally ill-suited for executive power, and a soothing flip-flopper who appears constructed along corporate specs. Which will sell out conservative principles first? Which even knows what conservative constitutionalist principles are?
Unless some sort of white knight appears suddenly to save us (Paul Ryan, Clarence Thomas, Sarah Palin....), these are our choices. I propose a test: Vote for Newt, and see how tough, smart, and principled Mitt in return is. Can he show that he is the true, electable conservative? Will he respond with conservative arguments or try to emphasize his moderation? This is not merely Gingrich blowing up and defeating himself. Romney has to win it, and by showing that he is more conservative (not that he has led a better family life, etc.). The only way we can test Romney is by voting for Newt, until he proves himself less of an electable conservative than Romney..
Might this not make Gingrich the winner? True, this would give him victories in Iowa (important to crush Paul, btw), New Hampshire (or a close second), and down south. But proportional delegate sharing will keep the second-place person close, and then we'll see who the strongest conservative will be, or whether we have a conservative at all. Both may flunk the test, but that is a problem for another day.
It would be a bad thing for the future of conservatism to hand the victory to Newt Romney immediately. We would be getting a flawed, erratically right-wing candidate, or a corporate construct who might have defeated Ted Kennedy by being more liberal. Either would be better than Obama, but we can do better than the two choices as they present themselves now. A long, drawn-out campaign will improve both candidates or reveal their fatal flaws.