Republican US Senate hopeful Richard Mourdock has expressed regret a day after suggesting pregnancies caused by rape were God's plan.
The Indiana candidate made the remarks while debating his Democratic opponent.
He told reporters on Wednesday he "abhors" rape and that if anyone "came away with any impression other than that, I regret it".
Mitt Romney's presidential campaign said he still backed Mr Mourdock, although he disagreed with his views.
Mr Mourdock's comments come two months after another Republican candidate caused a furious backlash when he said women's bodies had ways of preventing pregnancy after rape.
Mr Romney and President Barack Obama are campaigning hard for the 6 November US presidential election, in which women's votes could prove crucial.
During Tuesday night's debate with his Democratic challenger Joe Donnelly, Mr Mourdock was asked whether he believed abortion should be allowed in cases of rape or incest.
"I struggled with it myself for a long time, but I came to realise that life is that gift from God," he said.
"And, I think, even when life begins in that horrible situation of rape, that it is something that God intended to happen."
At a press conference on Wednesday, Mr Mourdock said he had been "humbled" by the reaction to his comments.
"If, because of the lack of clarity in my words, that they came away with an impression other than... life is precious and that I abhor violence and I'm confident that God abhors violence and rape... I truly regret it."
Mr Mourdock, a geologist by trade and the current Indiana state treasurer, said others were trying to "twist" his comments.
There are 33 Senate seats up for grabs in next month's elections, and the Republicans are hoping to win control of the chamber.
The Indiana seat was held safely at the last election by veteran Senator Richard Lugar, but he was ousted by voters in a Republican primary in May.
Mr Mourdock is backed by conservative groups, including the Tea Party, and has pledged no compromise with Democrats if he is elected.
What polling is available in the state suggests the he and his Democratic rival are in a tight race.
Several Republicans in close races, including Mr Romney, have distanced themselves from Mr Mourdock to varying degrees since Tuesday's comments.
Romney press secretary Andrea Saul said on Wednesday: "We disagree on the policy regarding exceptions for rape and incest, but still support him."
The Romney campaign says his administration would not oppose abortion in instances of rape.
The National Republican Senatorial Committee also stood by the Senate hopeful.
But other Republicans locked in tight election races spoke out against Mr Mourdock, such as Senator Kelly Ayotte of New Hampshire, who also cancelled a planned trip to campaign with him.
In Mr Mourdock's home state of Indiana, Representative Mike Pence, running for governor, called on the candidate to apologise.
Massachusetts Senator Scott Brown also said he disagreed with Mr Mourdock's views.
Democrats pounced on the debate remarks.
The Democratic National Committee has released an ad reminding voters of Mr Romney's recent endorsement of Mr Mourdock.
Obama campaign spokeswoman Jen Psaki told reporters that the president found the comment "outrageous and demeaning to women".
The Obama and Romney campaigns are desperately trying to win women's votes.
A gender gap poll among likely voters suggests that Mr Romney enjoys 14% more support among men than Mr Obama, while the president's support among women is 8% more than Mr Romney.
In August, Missouri Senate candidate Todd Akin almost derailed his own campaign when he said that in cases of "legitimate" rape, "the female body has ways to try to shut that whole thing down" and avert pregnancy.
At the time, Mr Romney and other senior Republicans urged Mr Akin to stand aside, but he refused, saying he had misspoken, and asked to be forgiven.
Mr Akin lost millions of dollars of funding, but has managed to keep his campaign afloat, polling an average of 5% behind incumbent Clare McCaskill.