Mitt Romney's campaign has refused to withdraw his support from Richard Mourdock, the Republican Senate candidate in Indiana who claimed that pregnancies from rape are "something that God intended to happen".

In a press conference on Wednesday morning, Mourdock, stood by his comments, apologising only for people misinterpreting them.

He said: "I said life is precious. I believe life is precious. I believe rape is a brutal act. It is something that I abhor. That anyone could come away with any meaning other than what I just said is regrettable, and for that I apologize. The apology – as I said before, roll this tape back – is if anybody misinterpreted what I said."

He added: "I absolutely abhor violence. I abhor sexual violence. I abhor rape. And I'm confident God abhors it."

Amid pressure for their presidential candidate to publicly distance himself from Mourdock, the Romney campaign said that while he disagrees with Mourdock on when abortion should be allowed, he would not withdraw his support.

Romney's press secretary Andrea Saul told journalists on the campaign plane that Romney "disagrees with Richard Mourdock, and Mr Mourdock's comments do not reflect Governor Romney's views", Buzzfeed reported.

Saul added: "We disagree on the policy regarding exceptions for rape and incest but still support him."

Both Mourdock and Romney's campaign said that an advert Romney recorded endorsing Mourdock's Senate bid would not be pulled.

"As senator, Richard will be the 51st vote to repeal and replace government-run healthcare. Richard will help stop the liberal Reid-Pelosi agenda. There's so much at stake. I hope you'll join me in supporting Richard Mourdock for US senate," Romney says in the ad.

Other Republican politicians have publicly distanced themselves from Mourdock following his comments, made during a debate with Democrat Joe Donnelly and others on Tuesday.

New Hampshire senator Kelly Ayotte had been scheduled to campaign with Mourdock in Indiana, but her spokesman, Jeff Grappone, told the Associated Press that Ayotte disagrees with Mourdock's comments, which do not represent her views. Grappone said Ayotte will remain in New Hampshire.

The Republican candidate for governor in Indiana, Mike Pence, said he "strongly disagree[s]" with Mourdock and has urged him to apologise.

In his press conference on Wednesday, Mourdock lamented his "less than fully articulate use of words".

"Humility is an important part of my faith," he said. "I am a much more humble person this morning because so many people mistook, twisted, came to misunderstand the points i was trying to make".

During Tuesday's debate, Mourdock, who is anti-abortion except in cases where the mother's life is at risk, was asked about his stance on abortion where a woman has been raped.

"I struggled with it myself for a long time, but I came to realize that life is that gift from God," Mourdock said. "And, I think, even when life begins in that horrible situation of rape, that it is something that God intended to happen."

Democrats seized on the comment and called upon Romney to withdraw his endorsement for Mourdock and pull his ad now airing in Indiana on behalf of the Senate candidate.

"It is perplexing that he wouldn't demand to have that ad taken down," Obama campaign spokeswoman Jennifer Psaki told reporters.

The campaign said President Obama found Mourdock's comments "outrageous and demeaning to women" and said the assertions were "a reminder that a Republican Congress working with a Republican president in Mitt Romney would feel that women should not be able to make choices about their own healthcare."

Romney was pro-choice as governor of Massachusetts, but is now anti-abortion except in certain cases. Vice-presidential candidate Paul Ryan is opposed to abortion in all cases, with no exceptions – on the face of it a stronger stance than Mourdock.

Mourdock did receive support from the national Republican senatorial committee.

In a statement, its chairman, John Cornyn, said: "Richard and I, along with millions of Americans – including even Joe Donnelly – believe that life is a gift from God. To try and construe his words as anything other than a restatement of that belief is irresponsible and ridiculous," Cornyn said.

Mourdock is not the first Republican to find himself in hot water over abortion beliefs. In August, Todd Akin, Republican Senate nominee from Missouri, said that pregnancy as a result of "legitimate rape" is rare as "the female body has ways to try and shut that whole thing down".

Just last week Republican congressman Joe Walsh of Illinois told reporters "you can't find one instance" where it has been necessary to perform an abortion due to the risk to the mother's life due to medical advances. Medical experts note that there are some cases where the only option in the case of complications sustained during pregnancy is to abort the foetus.

The Indianapolis Star reported that after the debate, Donnelly, the Democratic senate candidate, "shook his head over" Mourdock's comments. "I don't know any God who would ever intend something like that," Donnelly reportedly said.