Unfavorable views of Herman Cain have soared by 17 points in the face of allegations of past sexual harassment, including a sharp increase in negative views of Cain within his own party.

The latest ABC News/Washington Post poll finds that more Americans now see Cain unfavorably than favorably, by 44 percent to 29 percent, with the rest undecided. Favorability is a basic measure of any public figure’s personal popularity. It’s trouble when it goes negative.

Favorable views of Cain are essentially unchanged from a month ago – 31 percent then, 29 percent now. But the number who have no opinion of him has dropped steeply, while the share seeing Cain unfavorably has jumped from 27 percent in mid-October to today’s 44 percent.

The results suggest that essentially everyone who’s formed an opinion of Cain in the past month has done so negatively – a change concurrent with allegations by four women that Cain sexually harassed them in the 1990s when he headed a restaurant trade association in Washington, D.C.

More Republicans still see Cain positively than negatively, by 50-36 percent. But that compares with 52-17 percent last month, a 19-point rise in his unfavorable rating within his own party. His unfavorable rating also is up by 14 points among independents, as well as by 22 points among Democrats. And it’s up by 20 points among women, but also by 14 points among men.

In a measure of intensity, “strongly” unfavorable views of Cain now outnumber strongly favorable ones among the public overall by a 2-1 margin, 23 percent vs. 11 percent, after being essentially even last month.

One exception to the double-digit increases in Cain’s unfavorable rating is among Americans who identify themselves as very conservative, a core support group in his bid for the Republican presidential nomination. He’s viewed favorably by 48 percent of very conservatives and unfavorably by 28 percent, the latter up by a comparatively modest 7 points.

This poll was produced for ABC News by Langer Research Associates. Check back for more from the survey tomorrow on ABC’s Good Morning America.

METHODOLOGY – This ABC News/Washington Post survey was conducted by landline and cell phone among a random national sample of 1,018 adults from Nov. 9-13, 2011. The results have a margin of sampling error of plus or minus 3.5 points. This survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by SSRS/Social Science Research Solutions of Media, Pa.