In an editorial this morning (“Santorum’s Turn”), the guys at National Review are calling for Newt Gingrich to drop out of the race and let Santorum be the sole owner of the “not-Romney” mantle.

At the moment Rick Santorum appears to be overtaking Newt Gingrich as the principal challenger to Mitt Romney. Santorum has won more contests than Gingrich (who has won only one), has more delegates, and leads him in the polls. In at least one poll, he also leads Romney. It isn’t yet a Romney–Santorum contest, but it could be headed that way.

We hope so.

Really, it seems that NR’s comments and Santorum’s surge are based largely on character issues and leadership traits — of both Newt and Santorum:

Gingrich’s verbal and intellectual talents should make him a resource for any future Republican president. But it would be a grave mistake for the party to make someone with such poor judgment and persistent unpopularity its presidential nominee. It is not clear whether Gingrich remains in the race because he still believes he could become president next year or because he wants to avenge his wounded pride: an ambiguity that suggests the problem with him as a leader. When he led Santorum in the polls, he urged the Pennsylvanian to leave the race. On his own arguments the proper course for him now is to endorse Santorum and exit.

Santorum has been conducting himself rather impressively in his moments of triumph and avoiding characteristic temptations. He is doing his best to keep the press from dismissing him as merely a “social-issues candidate.” His recent remark that losing his Senate seat in 2006 taught him the importance of humility suggests an appealing self-awareness. And he has rightly identified the declining stability of middle-class families as a threat to the American experiment, even if his proposed solutions are poorly designed. But sensible policies, important as they are, are not the immediate challenge for his candidacy. Proving he can run a national campaign is.

Of course, Santorum did not take Gingrich’s advice to get out and stop splitting the vote, and since then, the former Pennsylvania senator has surged. I suppose Newt could have the same thing happen — but it seems highly doubtful.

If Newt is honest in his views that there must be only one “not-Romney” in the GOP primary race so that the conservative vote is not split, then maybe it’s time he backed up his rhetoric with deeds.