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Karl Rove's Crossroads USA took a cut from disgraced former President Richard Nixon's infamous White House recordings to fashion an ominous coda to its latest web video.

"We have a cancer within - close to the presidency, that's growing," we hear White House lawyer John Dean telling Nixon. "It's growing daily. It's compounding."

Of course, it's not Watergate we're meant to think of here, but the pro-Obama Super PAC Priorities USA ad that tied Romney health care policy to an uninsured woman's death from cancer.

Rove worked for the Nixon campaign in 1972, though he had no connection to the scandal that forced Nixon to resign the presidency.

More notable, though, than its rejection of the original attack - which, as we've seen, can be a tricky proposition - is the implication in the video that the Obama campaign cooked up the Priorities ad and then (illegally, if true) coordinated its production with the Super PAC .

Then, flashing through a montage of images showing members of the Obama re-election team in the same frames as Priorities USA organizers, a graphic pops up, saying, "Obama's own staff stood with Obama Super PAC."

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There's no evidence to suggest Obama For America (OFA) had anything to do with the making of the Priorities spot, at least no more than can be derived from the obvious personnel ties between the two groups.

That, of course, is not a strictly Democratic phenomenon - Romney's June retreat and fundraiser in Utah, with its commingling of campaign staff and outside money coordinators highlighted similar questions about the hazy line that separates the campaigns from the outside money groups.