* Congressman Akin asks for forgiveness in new Web ad
* Poll shows Akin slightly ahead of Democrat McCaskill
* Tuesday deadline to quit race without court order
WASHINGTON, Aug 21 (Reuters) - Republican Representative Todd Akin resisted pressure to quit the U.S. Senate race in Missouri on Tuesday, releasing a new ad apologizing for his inflammatory remarks about rape that have reinserted controversial abortion politics into the U.S. presidential campaign.
In an ad released online, Akin again apologized for his comments Sunday, when he claimed in a television interview that women could not get pregnant from "legitimate rape," even as senior Republicans condemned his remarks and called for him to step aside in the race.
Tuesday is the last day for candidates to file in the Missouri race, giving Republicans until later in the day to easily submit a replacement, if Akin decides to drop out.
"Rape is an evil act. I used the wrong words in the wrong way, and for that I apologize," Akin said in the Web video.
"The 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 added. Akin, noting that he is the father of two daughters, also said he wanted "tough justice" for rapists and expressed compassion for victims.
The Republican challenger is running against Democratic Senator Claire McCaskill in the Nov. 6 election. Akin has until 5 p.m. CDT/6 p.m. EDT (2200 GMT) Tuesday to drop out without a court order. He can quit as late as Sept. 25 if he produces an order to remove his name from the ballot.
His comments have become a distraction ahead of next week's Republican convention to nominate Mitt Romney for U.S. president and put the focus on social issues, rather than Romney's main message of the economy and jobs.
The controversy has also complicated Republican efforts to win the majority in the 100-member Senate.
But a poll conducted Monday night showed little effect from the controversy on the closely contested Missouri race.
Findings from Public Policy Polling showed Akin ahead of McCaskill 44 percent to 43 percent, even though the majority of Missouri voters said his rape comments were inappropriate. Before the controversy, the polling firm found Akin ahead 45 percent to 44 percent.
"Todd Akin still has a very decent chance at winning the Missouri Senate race," said Dean Debnam, president of the polling firm. "Voters were appalled by his comments about abortion, but not so much that they decided to vote Democratic when they were previously planning to support the GOP."
McCaskill's job approval is also an issue. The poll, which surveyed 500 likely Missouri voters, found that 41 percent of voters approve of her work in Congress, while 53 percent disapprove. The poll's margin of error was 4.4 percentage points.
On Sunday, Akin told KTVI television in St. Louis that the need for abortions in the case of rape was a tough question and that as far as pregnancy is concerned, "if it's a legitimate rape, the female body has ways to try to shut that whole thing down." Scientists and doctors have long discredited that theory.
Romney on Monday denounced Akin's remarks as "insulting, inexcusable, and, frankly wrong," and top Republicans have called on Akin to withdraw from the race and cut off advertising.
President Barack Obama and other Democrats also called Akin's remarks offensive.
Akin is a Tea Party-backed conservative who opposes abortion.
Along with Romney's vice presidential pick, Wisconsin Representative Paul Ryan, Akin proposed legislation in the U.S. House of Representatives that would have changed the legal definition of rape to "forcible rape" to limit federal funding for abortions. Critics said the measure could exempt victims of statutory rape.
Ryan also proposed legislation that would outlaw abortion with no exception for rape.