Bill Clark/CQ Roll Call/Getty Images

After days of ignoring Republican pleas to abandon his U.S. Senate campaign in Missouri, Rep. Todd Akin today received an even more damning message: A new Rasmussen poll shows that Akin, who held a tidy lead before making his controversial comments about rape and pregnancy, is now down 10 percentage points (48-38 percent) to incumbent Democratic Sen. Claire McCaskill.

Never fazed, the Akin campaign shot back with an unlikely proposal.

"The fact that Claire McCaskill is only polling at 48 percent after 72 hours of constant negative attacks on Todd Akin shows just how weak she is," Akin spokesman Perry Akin said in a statement. "If she can't break 50 percent after a week like this, Democrats should ask Claire to step down."

McCaskill, whose political career might well have been saved by Akin's moment of madness, went online to cast doubt on the validity of the survey.

"Rasmussen poll made me laugh out loud," she tweeted. "If anyone believes that, I just turned 29. Sneaky stuff."

McCaskill then linked to a story from the Milwaukee Journal Sentinel claiming Rasmussen, with its ties to high-powered Republican operatives like Karl Rove, had intentionally stretched the spread in an effort to push Akin out of the race.

The final deadline for Akin to withdraw is Sept. 25. After that his name cannot be replaced on the ballot. But there is no indication he's even considering it.

Today, he reported on his Facebook page, "Thousands and thousands of people have stepped up today and helped us raise over $100,000 in donations as small as $3. The message is loud and clear… the people of Missouri believe they should pick candidates, not party bosses or Washington elites."

The six-term congressman is trying to rally another $25,000 in donations by midnight.

Akin began his renewed campaign push on Twitter Wednesday, asking followers to "[Retweet] this if you won't let the liberal elite push you around!" and, "A lot of negativity has been driven my way by the liberal elite. Makes me even more thankful for your support #stillstanding."

Get More News at ABC Politics and a Different Spin at OTUS News Get the Note and the PM Note Delivered to Your Inbox