There is no power behind those ads. The candidate merely has to denounce the ad and we're done with it. If they DON'T denounce it --- then it is tacitly acceptable to the candidate.
That's all --- real simple.. Romney denounces one -- the W.H. denies responsibility for one but doesn't denounce it. Got it? Good..
Same power as in a major Newspaper editorial.. Adopt it -- Modify it -- or denounce it...
Just because someone endorses you or attempts to campaign on your behalf -- you don't lose control of your campaign..
When the Communist Party of the USA endorses Obama -- do we need to assume it came from his campaign? And they certainly don't NEED PERMISSION to do such a thing..
Denouncing an ad after it's run is like locking the barn door after the horses have left. The damage has been done; if the ad is offensive or unfair enough that no political entity will assume responsibility for it, then maybe it shouldn't see the light of day. Failing that, we can at least specify upfront that the ad has no support from anybody. If enough unsupported ads are run for a candidate or party, it can become a political liability, and maybe we'd see a little less of them.