Even as the National Republican Senatorial Committee – the campaign arm of Republicans in the Senate – swore up and down they would never return to help Todd Akin in his Missouri Senate race, most observers thought that, when things got tight, they would give in. And sure enough, that’s what’s happening, as they are the likely source of funds for a last minute ad boosting the Republican in his race against incumbent Claire McCaskill.

The $700,000 buy is being coordinated with the Missouri Republican Party. Politico reported on the details Wednesday.

“Only national committees — the NRSC or the Republican National Committee — or individual campaign committees that raise money in compliance with federal limits are permitted to shift funds to a state party for a coordinated ad buy,” Politico noted.

The RNC told TPM Thursday it’s not paying for the ad. The NRSC did not offer a similar denial.

“Decline to comment,” a spokesperson for the NRSC told TPM multiple times over Wednesday and Thursday.

The ad merges support for Mitt Romney, who is leading fairly easily in Missouri, with support for Akin, arguing “you don’t have to agree with everything he says, but you can be sure, in the Senate, Akin will vote for Romney’s policies.”

The NRSC is coming to the aid of Akin, in all likelihood, because they have almost no other path to victory in the Senate. Democrats are now favored to flip seats in Massachusetts and Maine, and have good chances in Indiana (where Republican Richard Mourdock got tripped up on an Akin-like abortion/rape comment), Arizona and Nevada. Republicans have to win a net of four seats to take over the chamber, and all of their pickups are in question, even in Nebraska, where Bob Kerrey just got the endorsement of Republican Chuck Hagel. Kerrey is still likely to lose, but races in North Dakota, Montana, Virginia, Wisconsin remain tight, with races in Ohio, Florida, Pennsylvania and Connecticut leaning strongly toward Democrats. The Missouri race represents one of the only paths to victory, and even then in a best-case scenario where all the questionable races tilt in favor of Republicans.

So why wouldn’t the NRSC, with their competency on the line, put out a lifeline for Akin in a red state, where at least one public poll shows a somewhat tight race? It only makes sense.