But Iowa’s political leaders, always looking ahead to the next campaign, worry that looks can be deceiving and that the prized role of the Republican caucuses is in jeopardy. Establishment Republicans fear that conservatives have become such a dominant force in the nominating process here that they may drive mainstream presidential candidates away.

That would relegate the caucuses to little more than a test of the party’s right-wing sentiment, and would do little to identify and propel the eventual nominee. …

“You’re going to see conservatives probably not play as much in New Hampshire, and you’re going to see moderates not play here,” Mr. Santorum said in an interview this month before he addressed the gathering of Christian conservatives here.

That is exactly what senior Iowa Republicans fear. And it is why some in the party are already taking steps to curb one of the more controversial elements of the caucus process: the Ames Straw Poll.