They know that he espouses conservative positions with Texas-size confidence and in a Texas accent. That's an advantage in a party in which 37 percent of the primary and caucus votes were cast in the 14 Southern states in 2008.
But Perry's support could prove just as evanescent as Romney's. He is out of step with conservative orthodoxy on one important issue, immigration, just as Romney is on the individual mandate in his Massachusetts health care plan.
As I see it, Romney is handicapped because he started running too long ago, while other candidates are handicapped because they started too recently.
Romney's 2008 strategy was almost a carbon copy of George W. Bush's eight years before: combine some compassionate conservatism (Romneycare) with conservative stands on cultural issues like abortion (which was not entirely consistent with his record).
Now he is running as a businessman who knows how to create jobs. He has been deft at avoiding attacks on Romneycare, but it is still a problem.
Perry, in contrast, did not contemplate running until late spring. His 2010 book "Fed Up!" is filled with incendiary rhetoric that may prove problematic. As he himself said, "I wouldn't have written that book if I was going to run for the presidency of the United States."
It's easy to see how the debates could become a contest in which each of the two leading candidates attempt to undermine the other's conservative bona fides. Others, notably Michele Bachmann, whose victory in the Aug. 13 Ames straw poll in Iowa was overshadowed by Perry's candidacy announcement the same day in Charleston, S.C., have an incentive to do so, as well.
The challenge for Perry and Romney, who both have more executive experience than candidate Obama had in 2008, is to show the discipline and focus to establish themselves as serious general election candidates with better ideas about how to jump-start the economy than the hapless incumbent.
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