The conservative National Review published an extraordinary editorial Wednesday, urging Republican voters not to cast their primary ballot for Newt Gingrich.

The reasons cited for the non-endorsement are nothing voters haven't heard already: "His impulsiveness, his grandiosity, his weakness for half-baked (and not especially conservative) ideas," the editorial offered, all of which led to a larger point - that Gingrich would cost Republicans a chance at a 2012 sweep of the White House and Congress, with all the conservative policy achievements that could follow.

Said the editorial: "If he is the nominee, a campaign that should be about whether the country will continue on the path to social democracy would inevitably become to a large extent a referendum on Gingrich instead. And there is reason to doubt that he has changed."

What's extraordinary isn't that the National Review is putting ink to the widespread frets of Republicans. It's the risk the editorial takes - that if Gingrich wins the nomination despite so many conservative pleas similar to this one, Republicans will be left with a candidate so many in the party have gone on the record as fearing.

Certainly, many conservatives would vote for nominee Gingrich anyway in the general election, given the alternative. But elections are won in part on enthusiasm, and Gingrich would be hitting November with a clearly conflicted base. It's hard for the National Review to walk back from this on Gingrich: "He appears unable to transform, or even govern, himself. He should be an adviser to the Republican party, but not again its head."

Are the conservative attacks on Gingrich just part of primary politics? To a degree. Hillary Clinton supporters were hard on Barack Obama in 2008, but in the end, prominent liberals didn't cross the bridge from "uncertain commodity" to "unfit leader" with Obama. That's what we're seeing with conservatives and Gingrich.