“I like Romney’s message,” Mr. Brumby said, “but I just think Ryan is the sharper of the two, and I think Ryan is more acclimated toward and relates better to the working class.”

Conservatives initially saw the selection of Mr. Ryan as a hopeful sign that Mr. Romney had fully embraced their small-government agenda and eagerness to turn the election into a head-on clash of ideologies. But now, with Mr. Romney encountering a host of problems and Republicans openly fretting about the outcome in November, Mr. Ryan’s slow fade back into the secondary and sometimes afterthought role traditionally played by running mates has given conservatives a new outlet for frustration over the state of the race…

If the Republican ticket loses in November, the rush by Mr. Ryan and other 2016 hopefuls to position themselves for the Iowa caucuses “is going to look like Best Buy the night after Thanksgiving,” said Craig Robinson, a former political director of the Republican Party of Iowa. “I hate to say this, but if Ryan wants to run for national office again, he’ll probably have to wash the stench of Romney off of him.”