Conversations with nearly two dozen voters across the state revealed little interest among Republicans in the back-and-forth over Mr. Romney’s financially rewarding days as a corporate executive. In several cases, people said they were drawn to Mr. Romney after hearing the pointed attacks from his rivals.

When Donald Hare, 69, a retiree on Hilton Head, was asked if he was a supporter of Mr. Romney, he declared, “I am now.” He added: “What Newt did convinced me. He got into the gutter on Governor Romney.”

But while Gov. Nikki R. Haley of South Carolina introduced Mr. Romney at nearly every campaign stop last week as “the only one that can beat President Obama this next election,” his rivals argued otherwise. A variety of polls show that Mr. Romney has a lead in the race, but not a commanding one…

“He was running an investment company that put money into distressed corporations and turned them around, reduced expenses or liquidated them. That’s the business,” Mr. Schaaf said. “To be criticized for that is kind of a dirty dig.”