ST. LOUIS -- Rep. Todd Akin vowed to fight on in his embattled Senate campaign, but a significant deadline loomed Tuesday that was bound to intensify pressure on the Missouri congressman to abandon the race over his comments that women's bodies can prevent pregnancies in cases of "legitimate rape."
Akin has been frantically trying to salvage his once-promising bid against incumbent Democrat Claire McCaskill in a race long targeted by the GOP as crucial to regaining control of the Senate. But ominous signs were mounting against the six-term legislator from suburban St. Louis, most notably the apparent loss of millions of dollars in campaign advertising money.
He went on two conservative radio shows Monday, pledging to keep the campaign alive, even as some from within his own party urged him to step aside. Early Tuesday, Akin posted a video online in which he apologized but made no mention of the race.
The decision has some urgency. Missouri election law allows candidates to withdraw 11 weeks before Election Day. That means the deadline to exit the Nov. 6 election is 5 p.m. Tuesday. Otherwise, a court order would be needed to remove a name from the ballot.
In a radio interview with former Republican presidential candidate Mike Huckabee, Akin repeatedly apologized for the remarks but also vowed to stay in the race.
"The good people of Missouri nominated me, and I'm not a quitter," Akin said.
The uproar began Sunday, when St. Louis television station KTVI aired an interview in which Akin was asked if he would support abortions for women who have been raped.
"It seems to me, first of all, from what I understand from doctors, that's really rare. If it's a legitimate rape, the female body has ways to try to shut that whole thing down," Akin said.
In the interviews with Huckabee and Sean Hannity, Akin acknowledged that rape can lead to conception.
"Rape is never legitimate. It's an evil act. It's committed by violent predators," Akin said. "I used the wrong words the wrong way."
But the damage had been done. The comments drew a sharp rebuke from fellow Republicans, including presumptive presidential nominee Mitt Romney and his vice presidential choice, Rep. Paul Ryan, of Wisconsin.
The Senate's top Republican, Mitch McConnell, said Akin's comments might "prevent him from effectively representing" the Republican Party. He called on Akin to "take time with his family" to consider whether he should continue in the Senate race.
Two other Republican senators, Scott Brown of Massachusetts and Ron Johnson of Wisconsin, urged Akin to resign.
Akin also apparently lost a key source of funding. Sen. John Cornyn, head of the National Republican Senatorial Campaign Committee, told Akin that $5 million in advertising set aside for Missouri will be spent elsewhere and that Akin will get no other help from the committee, according to a committee official who spoke on condition of anonymity because the conversation was private.
Cornyn told Akin that he was endangering the GOP's hopes of getting a Senate majority by staying in the race, the official said.
Republican frustration grew Tuesday. Two GOP officials, speaking on the condition of anonymity because they did not want to irritate Akin, said party officials seeking to talk with him were having trouble reaching him Monday night and Tuesday morning.
Akin campaign spokesman Ryan Hite declined Tuesday to reveal Akin's whereabouts but said he was not in his suburban St. Louis campaign office. Hite said the campaign may release information about his public schedule later.
At least one political interest group that has pounded McCaskill with attack ads, the Karl Rove-backed American Crossroads, also pulled its ads from Missouri.
The apology video Akin posted on YouTube early Tuesday was an apparent attempt to claw back some of that funding.
"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," he said in the video.
President Barack Obama said Monday that Akin's comments underscore why politicians -- most of whom are men -- should not make health decisions on behalf of women.
"Rape is rape," Obama said. And the idea of distinguishing among types of rape "doesn't make sense to the American people and certainly doesn't make sense to me."
It was just two weeks ago that Akin was at the top of the political world in Missouri after winning a hotly contested three-way battle with millionaire businessman John Brunner and former state Treasurer Sarah Steelman for the right to challenge McCaskill in the November election. Missouri has grown increasingly conservative in recent years, and McCaskill is seen as vulnerable.
She was not among those calling for her opponent to get out of the race.
"What's startling to me is that (Republican) Party bigwigs are coming down on him and saying that he needs to kick sand in the face of all the primary voters," McCaskill said at a campaign event Monday in suburban St. Louis. "I want Missourians to make a choice in this election based on policy, not backroom politics."
One anti-abortion group expressed support for Akin, while another called on him to step aside.
Missouri Right to Life, which opposes a woman's right to get an abortion even in cases of rape and incest, said Akin's "consistent defense of innocent unborn human life clearly contrasts" with McCaskill's position.
But the Christian Defense Coalition called on him to withdraw.
Names are being floated about a possible replacement for Akin. A favorite is Tom Schweich, the state auditor who was courted to run for Senate earlier this year but declined.
Other names mentioned include former Sen. Jim Talent, who lost to McCaskill in 2008; former Gov. Matt Blunt, the son of Missouri's other senator, Roy Blunt; two members of Missouri's House delegation, Blaine Luetkemeyer and Jo Ann Emerson; and Akin's two unsuccessful primary opponents, Brunner and Steelman.
Talent, who lost his seat to McCaskill in 2006, said Monday he had been asked to run but declined.
If Akin were to leave, state law gives the Republican state committee two weeks to name a replacement. The new candidate must file within 28 days of Akin's exit.
The American Congress of Obstetricians and Gynecologists said a woman who is raped "has no control over ovulation, fertilization or implantation of a fertilized egg (i.e., pregnancy). To suggest otherwise contradicts basic biological truths."
Between 10,000 and 15,000 abortions nationwide occur each year among women whose pregnancies resulted from rape or incest. An unknown number of babies are born to rape victims, the group said.
Research on the prevalence of rape and rape-related pregnancies is spotty. One estimate published in 1996 said about 5 percent of rapes result in pregnancy, or about 32,000 pregnancies among adult women each year.
Associated Press writers Henry C. Jackson in Washington; Lindsey Tanner in Chicago; Jim Suhr in St. Louis; and Chris Blank and David Lieb in Jefferson City, Mo., contributed to this report.