Last updated at 9:02 p.m. with the Romney campaign's response.
“First of all, from what I understand from doctors, (pregnancy from rape) is really rare,” Akin told KTVI-TV in a clip posted to YouTube by the Democratic super PAC American Bridge. “If it’s a legitimate rape, the female body has ways to try to shut that whole thing down.”
Akin added: "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.”
Akin issued a statement Sunday afternoon saying he misspoke.
"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," he said. "I recognize that abortion, and particularly in the case of rape, is a very emotionally charged issue. But I believe deeply in the protection of all life and I do not believe that harming another innocent victim is the right course of action."
Akin's statement threatens to recast a Senate race in which he starts as the favorite, but national Republicans are concerned about his ability to execute a winning strategy. Akin won the GOP nomination two weeks ago -- a result that Democrats hailed as a potential game-changer in a tough race for them.
Sen. Claire McCaskill (D-Mo.) and national Democrats actually spent money in the GOP primary to help get Akin through it. That strategy, at least in this case, appears to be paying dividends.
McCaskill said she was outraged by Akin's claim.
"It is beyond comprehension that someone can be so ignorant about the emotional and physical trauma brought on by rape," McCaskill said in a statment. "The ideas that Todd Akin has expressed about the serious crime of rape and the impact on its victims are offensive."
Akin's claim is one that pops up occasionally in social conservative circles. A federal judge nominated by President Bush in the early 2000s had said similar things, as have state lawmakers in North Carolina and Pennsylvania.
Politicians and activists who espouse this view often suggest that women who haven't been raped will claim to have been raped in order to obtain an abortion. An Idaho state lawmaker apologized earlier this year after urging doctors to make sure women who claimed they had been raped were sure of that fact.
Akin himself has suggested in the past that women may claim to be raped as a strategy during divorce proceedings.
Needless to say, this is territory that GOP leaders would rather not have Akin wander into. Getting into the particulars of "legitimate rape" (as opposed to what?) and the female reproductive system has the potential to make this a headache for the GOP and take the focus off of McCaskill and President Obama, who is unpopular in Missouri.
The Romney campaign issued the following statement late Sunday distancing itself from Akin's comments:
Governor Romney and Congressman Ryan disagree with Mr. Akin’s statement, and a Romney-Ryan administration would not oppose abortion in instances of rape.
According to a 1996 study, approximately 32,000 pregnancies result from rape annually in the United States, and about 5 percent of rape victims are impregnated.
"Rape-related pregnancy occurs with significant frequency," the study says, according to an abstract. "It is a cause of many unwanted pregnancies and is closely linked with family and domestic violence."
Akin is also staking out some of the most socially conservative territory possible on this issue. Missouri is pretty socially conservative, but even many Republicans believe in abortion exceptions for rape and incest. A recent Gallup poll showed just 20 percent of Americans believe in no exceptions for abortion.