Last week, the Des Moines Register did some anecdotal research in the middle of the breathless scandal coverage surrounding Herman Cain, and found that likely Iowa caucus-goers didn’t really care much about the vague, second-hand allegations percolating in the national news.  Yesterday, RCP reported that a more scientific survey from Insider Advantage shows the exact same result.  Cain now leads in Iowa by 15 points over Mitt Romney, who finds himself just a margin of error ahead of a third-place Newt Gingrich:

Despite being embroiled in controversy last week, Herman Cain leads the Republican presidential field by 15 percentage points in Iowa, according to a new poll taken four days after news broke that the Atlanta businessman had been accused of sexually harassing women while head of the National Restaurant Association in the late 1990s.

Cain attracts 30 percent support from Iowa GOP caucus-goers, according to the Insider Advantage poll. Former Massachusetts Gov. Mitt Romney places a distant second with 15 percent. Former House Speaker Newt Gingrich rounds out the top three with 12 percent. The remaining candidates poll in the single digits: Texas Rep. Ron Paul garners 9 percent, Minnesota Rep. Michele Bachmann — who won the straw poll in Ames in August — receives 8 percent, Texas Gov. Rick Perry earns 6 percent, and former Utah Gov. Jon Huntsman has 2 percent.

This poll has a fairly decent sample size of 507 likely caucusers.  Normally the Register would have the most reliable polling for caucusing, but IA has a pretty good reputation as well. What makes this interesting is the timing of the poll; they took the survey on Thursday, after more than three days of non-stop discussion of the Cain “scandal,” which seems to have had no effect on Iowa Republicans.

That isn’t the only surprise in the poll. Cain’s double-digit lead will come as a disappointment to the other candidates, who have spent more time and have better organization in the state.  For most of those in this poll, the money they have spent in Iowa has not paid off at all, and now they have to watch as a candidate who has barely done anything in a state well-known for its demands on presidential aspirants has apparently fallen under the Cain spell from long distance. Rick Perry has to feel especially frustrated, considering the time and energy he has expended there.

Finally, take a look at Gingrich’s slow climb in Iowa as well.  Romney would benefit from a second-place finish in Iowa, since it would beat expectations.  No one expected him to compete well, and he has been deliberately low key in his organizing there.  But a third-place finish behind Cain and Gingrich would be a bigger problem for his campaign to explain.  Gingrich now leads Romney among male voters, and Gingrich’s charm offensive of the last few months might garner him more momentum in Iowa as the caucuses approach — especially after his Reagan Dinner performance that came the day after this poll was taken.  If Cain stumbles and Romney doesn’t catch fire, Gingrich is putting himself in position to reap the benefits.