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Republican Senate candidate Todd Akin said Friday that he had been arrested during an anti-abortion protest about two decades ago but didn't provide details of where or when the event occurred.

Akin also defended his characterization of Democratic U.S. Sen. Claire McCaskill as not being "ladylike" in a recent debate, saying he used the term "just as the English language uses those terms."

Akin's comments -- whether mistaken or intentional -- have loomed large in Missouri's Senate race since shortly after he won the Aug. 7 Republican primary. They also have generated ripples through national politics, including the presidential race and Republicans' efforts to gain the four seats necessary to win control of the Senate from Democrats.

In a video circulating widely on the Internet Friday, Akin is seen discussing his involvement in an anti-abortion demonstration and says "you know, don't tell anybody I'm a jail bird." He also says in the video that "a bunch of us sat in front of these doors and the police gave us a ride to the free hotel for a while, and you know how it goes."

Asked at a press conference Friday in Kansas City to confirm the arrest, Akin said: "Yeah, well, certainly. Probably about 25 years ago or so I was involved in some peaceful protests. As I've made very clear I don't apologize for being pro-life. I stand up for the things I believe in."

His campaign promised to provide details of the arrest later Friday.

Akin also defended his comment that McCaskill wasn't very "ladylike" during their Sept. 21 debate, in which McCaskill forcefully criticized Akin.

Akin said Thursday that McCaskill "came out swinging" in the debate, and contrasted the approach with her 2006 debates against then-Sen. Jim Talent, when Akin said, "she had a confidence and was very much more sort of ladylike and all."

McCaskill said Friday that some of Akin's remarks have left her "a little speechless."

"I'm hoping that people will weigh in and defend me that I was polite and calm. This wildcat, you know, furious and unladylike is kind of a headscratcher," she said.

But Akin did not back off his assertion.

"We've got a couple words in the English language, one is a gentleman and a lady," Akin said Friday. "I think those are pretty self-explanatory terms, and I was using them just as the English language uses those terms. So you know it seems that some people want to take offense at words. It seems to me the offensive thing is the voting record that's destructive to the people of our state."

Last month, Akin told a TV interviewer asking about his opposition to abortion that women's bodies have ways of averting pregnancy in cases of "legitimate rape." Akin has apologized repeatedly since then but rejected calls from top Republicans -- including presidential nominee Mitt Romney -- to quit the race. Meanwhile, Akin has lost the financial backing of the National Republican Senatorial Committee and the deep-pocketed Crossroads group affiliated with GOP strategist Karl Rove.

Democrats have attempted to link Akin's "ladylike" comment to his remark about "legitimate rape" to suggest he is insensitive to women and to help drive their own fundraising efforts.

The Democratic National Committee and Emily's List, which backs Democratic women who support abortion rights, both cited the remarks in fundraising emails Thursday. On Friday, New York Sen. Kirsten Gillibrand highlighted Akin's remarks as the centerpiece of an online fundraising drive to raise $75,000 for McCaskill in two days.

Akin also received a recent fundraising boost, picking up the endorsement Thursday of the Senate Conservatives Fund, whose members pledged $290,000 for his campaign.

On Friday, former Missouri Sen. Kit Bond said he now supports Akin's campaign. Bond had been part of a coalition of past and present Republican Missouri senators who had called on Akin to quit last month. Missouri Sen. Roy Blunt also reversed course and backed Akin earlier this week, though former Sen. John Danforth reiterated that he would not do so.

"Todd's comments were unacceptable but he's apologized, believe his regret is sincere, and it is time to focus on the national stakes in this election," Bond said in a written statement.