LAS VEGAS — Mitt Romney absorbed blows from most of the presidential candidates in Tuesday's CNN debate, but Romney's campaign seems to have its sights set on Rick Perry.

"Rick Perry's a desperate man. His decision to resort to negative attacks and personal cheap shots against Mitt Romney was booed by the audience," said Eric Fehrnstrom, one of Romney's top advisers, in the spin room following the debate.

Although Herman Cain is currently Romney's biggest threat in the polls, it was Perry whose meteoric rise after he entered the race in August raised the specter of a viable Romney alternative emerging.

Fehrnstrom also responded to Perry's refusal to denounce a pastor who called Mormonism a cult the same day he endorsed Perry for president. Romney is a Mormon, and Nevada, the site of Tuesday's debate, has a sizable Mormon population.

"There are some people who will vote against Mitt Romney because of his religion. There's nothing we can do about it," Fehrnstrom said.

Romney's campaign also sent out two releases during the debate attacking Perry's record on immigration and job creation in Texas. Perry, meanwhile, sent out a half-dozen releases attacking Romney.

"This is a campaign about character," said Ray Sullivan, Perry's top spokesman, after the debate. He argued that Romney's past support for positions he and the other candidates now oppose calls into question his sincerity and consistency.