Republican Todd Akin has defiantly refused to step down from the Senate election race as he staged his first public event since controversial comments about rape victims.
The 65-year-old congressman held a news conference in St Louis, Missouri, as he attempted to shift the focus back to incumbent Senator Claire McCaskill.
He sparked uproar this week after he said women's bodies were able to prevent pregnancy in cases of "legitimate" rape and later claimed he had "misspoke".
The remarks provoked a rebuke from presumptive Republican presidential candidate Mitt Romney and calls for him to quit the Senate race.
But he has refused to concede, despite Republican donors pulling millions of dollars in campaign advertising for his election.
Romney brought up Barack Obama's birth certificate during a Michigan rally And supporters have rounded on party figures for attempting to force him to step down.
Speaking at the news conference, he said: "We are going to be here through the November election, and we are going to be here to win.
"I may not be the favourite candidate of some people within the Republican establishment, but the voters made a decision."
Mr Akin trails his Democrat opponent by 10 points, but prior to the controversial comments he was ahead in the polls.
US Capitol Police revealed they were investigating a possible threat made against Mr Akin on Thursday.
It comes after Mr Romney took a swipe at President Barack Obama during a rally in his home state of Michigan.
Speaking in front of 7,000 people days before the Republican National Convention, he referenced the "birther" theory that Mr Obama was not born in the US.
He said: "I love being home in this place that Anne and I were raised. Where both of us were born. Anne was born in Henry Ford hospital. I was born in Harper hospital.
"No one has ever asked to see my birth certificate, they know that this is the place we were born and raised."
Advisor Kevin Madden later said: "The governor has always said, and has repeatedly said, he believes the president was born here in the US.
"He was only referencing that Michigan, where he is campaigning today, is the state where he himself was born and raised."
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