The Republican vying for Democrat Claire McCaskill's Senate seat in Missouri said Sunday that he misspoke during an earlier television interview when he said pregnancies in the case of "legitimate rape" are rare and that women have a biological ability to prevent pregnancy in such cases.

Rep. Todd Akin (R., Mo.), who recently won the GOP primary to run for Ms. McCaskill's seat, made his comments in an interview broadcast Sunday by St. Louis television station KTVI and posted on its website. Mr. Akin was asked about whether abortion should be legal in the case of rape.

"From what I understand from doctors, that's really rare," Mr. Akin said of pregnancy caused by rape. "If it's a legitimate rape, the female body has ways to try to shut that whole thing down. But let's assume that maybe that didn't work or something…I think there should be some punishment, but the punishment ought to be on the rapist and not attacking the child."

In a statement later, Mr. Akin said: "In reviewing my off-the-cuff remarks, it's clear that I misspoke in this interview and it does not reflect the deep empathy I hold for the thousands of women who are raped and abused every year. Those who perpetrate these crimes are the lowest of the low in our society and their victims will have no stronger advocate in the Senate to help ensure they have the justice they deserve."

Ms. McCaskill, whose seat is widely seen as one of the Democrats' most vulnerable to a GOP pickup, was quick to seize on the issue. Her campaign featured Mr. Akin's earlier comments on its website and sought contributions.