[P]olitical scientists Martin Cohen, David Karol, Hans Noel, and John Zaller argue that one thing is likely to make political parties nominate a centrist: losing. Specifically, the longer a party is out of power—that is, the more presidential elections it has lost in a row—the more likely it will nominate a moderate candidate. Parties that have been out of the White House for only a short time are more willing to nominate a candidate closer to the ideological pole. . . .
[T]his evidence hardly portends that Rick Perry will win and Mitt Romney will lose. But it does suggest that 2012 could be a year in which the GOP does, to quote Mr. Cohen and colleagues, “test the limits of voter tolerance” by nominating a candidate like Mr. Perry. The authors’ data would suggest that for conservative activists, this is likely their best year to nominate their preferred candidate.