Yesterday was the final day that Todd Akin could take himself off the Missouri Senate ballot. But I think the national Republicans who desperately wanted this to happen gave up on the idea long ago. Clearly Akin marches to his own beat, and wouldn’t be swayed even by the cutoff of funds. Some conservative movement members have slowly been inching their way back into the race, with Newt Gingrich campaigning with Akin this week, and Jim DeMint’s PAC likely to send him some money.

So it was no surprise that Akin, in his final news conference before the deadline, announced that he was in it to win it.

“I was given a trust” in the August Republican primary that put him on the ballot, Akin told about 200 enthusiastic supporters in a ballroom at the downtown Renaissance. “. . . A number of people have asked me, ‘Are you quitting?’ . . . I don’t believe that is really my decision.”

He added, to heavy cheering from the crowd: “I have a purpose going into November and that’s to replace Claire McCaskill.”

So Republicans are saddled with an extreme candidate in Missouri who only has a passing knowledge of female anatomy. That said, it’s entirely possible that he’s a decent fit for the state, and winning is not out of the question. So Claire McCaskill’s campaign, which had been muted in their responses to Akin until the deadline for withdrawing from the ballot passed, fired off both barrels as soon as the deadline hit. The result is the ad above.

The negative ad rehashes a bunch of Akin’s more controversial comments, but closes by saying that he believes that “only some rapes are legitimate.” It’s the first time McCaskill’s campaign has referenced Akin’s remark about rape and pregnancy in a TV ad.

McCaskill and whatever Democratic groups decide to participate in Missouri are in a race against time. They have a massive money advantage at the moment. Akin has virtually nothing save for the possible funds from DeMint’s PAC, and national Republican groups have yet to return to the race. There’s a small window to completely define Akin and put him so far behind that Republicans couldn’t catch up even if they returned to funding his campaign.

Meanwhile, the calculation for staying out of Akin’s race is really more about OTHER Republican races, not the Senate race in Missouri. Akin has contributed to this drop in the national ticket across the board, bringing back all the “war on women” actions over the past two years. If Republicans break with their promise and give money to Akin, it’s not so much that race, but random House races in suburban areas with lots of independents that will suffer. Still, if the GOP has no other options to capture the Senate, I’d expect them to take the risk. That hesitation, however, gives McCaskill an opportunity to end the race before it begins.