“Are they willing to let a guy who should win a seat lose a seat because they sat on their hands?”

“Akin has come to symbolize a version of the Republican Party that’s just not acceptable to an awful lot of people,” Mr. Danforth said in an interview. “I don’t know if he can win or not in the election in the Senate race, but I think this is bigger than one Senate seat. I think it’s the brand of the Republican Party, and I think he taints the Republican Party.”

While Mr. Danforth is maintaining his opposition to Mr. Akin, others are returning to his corner. Republican Senator Roy Blunt of Missouri, as well as Christopher S. Bond and Jim Talent, both former Republican senators from the state, recently endorsed Mr. Akin after initially urging him to step aside after his comments about rape and abortion…

Mr. Akin has received considerable pledges from some groups. The Senate Conservatives Fund has started a drive to raise $300,000 for him, and as of Friday evening it had collected more than $270.000. Freedom’s Defense Fund has spent more than $66,000 on the race so far. Last weekend, CitizenLink, an evangelical group affiliated with Focus on the Family, spent $52,413.67 on the race.

But Mr. Akin is being vastly outspent by Ms. McCaskill — who reported raising $5.8 million since July 1 — and her allies.