NEW BEDFORD, Mass. — Heated exchanges over the “war on women” have suddenly come to dominate the closely watched Senate race here, thanks to an obscure Republican congressman from Missouri.

Soon after the congressman, Representative Todd Akin, said in an interview broadcast on Sunday that women who are victims of “legitimate” rape rarely become pregnant, both Senate candidates here seized on the comments for their own benefit.

Senator Scott P. Brown, a Republican who is locked in a tight re-election battle against Elizabeth Warren, used them to distance himself from his party — a necessity in deep-blue Massachusetts. He was the first Republican senator to call on Mr. Akin to quit his race for the Senate. As Mr. Brown told a group of women here on Tuesday, he was feeling a little heady from the experience.

“Gail and I were laying in bed last night and talking a little bit, as we do every night,” he said, “and I said: ‘Honey, can you imagine? Here I am, Scott Brown from Wrentham, and I’ve got a truck that’s got 238,000 miles on it and, you know, something like this comes up and I’m the first guy in the country to even bring it up and tell the guy to step down,’ ” Mr. Brown said.