Media playback is unsupported on your device Media caption Missouri congressman Todd Akin uses his new TV ad to ask for "forgiveness"

US candidate Todd Akin, who caused uproar by claiming women's bodies could prevent pregnancy in cases of rape, has again refused to stand aside.

The Republican congressman said people had over-reacted to his remarks, as he defied pressure from his party to bow out of the Senate race in Missouri.

He has asked to be forgiven for Sunday's remarks on "legitimate rape", which prompted outrage and bafflement.

The gaffe could sink his challenge to Democratic incumbent Claire McCaskill.

Correspondents say Republicans fear the backlash could endanger their campaign to win control of the US Senate in November's elections.

'Taking a stand'

On conservative radio host Mike Huckabee's show on Tuesday, Mr Akin announced he would not be quitting the race.

He described the response to his comments as a "little bit of an over-reaction", saying he had mistaken "one word in one sentence on one day".

Pregnancy and rape There are more than 32,000 pregnancies from rape each year, the Centers for Disease Control says

A woman who has been raped "has no control over ovulation, fertilization or implantation of a fertilized egg (pregnancy)," says the American Congress of Obstetricians and Gynecologists

The same group says that annually, between 10,000 and 15,000 abortions take place as a result of incest or rape

"By taking this stand, this is going to strengthen our country," Mr Akin said. "I hadn't done anything morally or ethically wrong, as sometimes people in politics do."

The sixth-term lawmaker said he was staying in because there were voters who did not feel represented by the major political parties.

But Republican presidential candidate Mitt Romney later joined the chorus of Republican calls for Mr Akin to stand aside because of his "offensive and wrong" comments.

Last week Mr Akin had a comfortable lead in opinion polls over Senator McCaskill in the Midwestern state of Missouri, which has leaned increasingly conservative in recent years.

Then on Sunday, he was asked by local news station KTVI-TV about his no-exceptions view on abortion.

The 65-year-old lawmaker replied: "It seems to me, from what I understand from doctors, that is really rare.

"If it's a legitimate rape, the female body has ways to try to shut that whole thing down."

The American Congress of Obstetricians and Gynecologists has said Mr Akin's claim "contradicts basic biological truths".

He also went on Mr Huckabee's radio on Monday to resist calls from prominent Republicans to drop out of the race.

In a face-to-face video message on Tuesday, Mr Akin said: "Rape is an evil act. I used the wrong words in the wrong way, and for that I apologise.

He added: "Fact is, rape can lead to pregnancy. The truth is, rape has many victims. The mistake I made was in the words I said, not in the heart I hold. I ask for your forgiveness."

'Gutless little twerp'

Five prominent Missouri Republicans also came forward on Tuesday to say they do not believe Mr Akin should remain in the race.

Media playback is unsupported on your device Media caption Todd Akin on "legitimate rape" - Video courtesy FOX 2 KTVI

Mitch McConnell, the top Republican in the Senate, has also suggested the Missouri congressman should reconsider his candidacy.

But even as prominent conservatives were criticising the congressman's comments, the Republican Party was reportedly ratifying a call for a constitutional ban on abortion, without any exception for rape or incest.

The position was to be the subject of a vote at the Republican national convention in Tampa, Florida, next week.

The National Republican Senatorial Campaign Committee has reportedly told Mr Akin that $5m (£3.2m) in advertising set aside for Missouri would now be spent elsewhere.

The Karl Rove-backed Crossroads organisation also pulled its ads from Missouri.

But Senator McCaskill, whose campaign appears reinvigorated by her Republican challenger's slip-up, did not join calls for him to stand aside.

She said Republicans were trying to "kick sand in the face" of their party's voters in Missouri who selected Mr Akin this month as their candidate.

On Monday evening, CNN television host Piers Morgan labelled Mr Akin a "gutless little twerp" for pulling out of an appearance on his show.

US media reacts

A New York Times editorial says that while Republicans are distancing themselves from Akin's comments, his views "expose a widely held belief among many fierce abortion opponents that a rape exception will be abused by women whose rapes were not 'legitimate'".

The Washington Post expands on that argument, saying: "Unfortunately, Mr Akin's remarks are not the first, nor are they likely to be the last, in a long-running effort to downplay the horror of rape as a way to restrict access to abortion. What they're really saying is that not all rape victims are victims, and so we shouldn't worry if they have to deal with unwanted pregnancy."

And the Atlantic says proponents of no-exception anti-abortion policies have tried to downplay or deny the occurrence of rape- or incest-related pregnancies: "The idea that trauma is a form of birth control continues to be promulgated by anti-abortion forces that seek to outlaw all abortions, even in cases of rape or incest."

Meanwhile, the San Fransisco Chronicle says Democrats are trying to link Mr Akin's comments to vice-presidential candidate Paul Ryan's position on abortion: "This is the Democratic National Committee playbook: Delegitimize a respectable position - that abortion is the taking of innocent life - not by refuting it but by assessing guilt by association."