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An early advance in Paul Ryan's popularity fell flat in the latest ABC News/Washington Post poll, with views of the presumptive Republican vice presidential nominee stabilizing at essentially an even split. Ryan's consolation: Joe Biden does no better overall - and worse among potentially swing-voting independents.

The public divides by 41-37 percent in favorable vs. unfavorable views of Ryan. He had gained 15 percentage points in popularity immediately after Mitt Romney announced his selection Aug. 11. That's slowed to a standstill since, +3 more points in the ensuing week.

See PDF with full results, charts and tables here.

Biden, though, with more time in the spotlight, has no better results. Americans divide exactly evenly, 43-43 percent, in their basic assessments of the vice president, a far cry from his much better ratings in the surge of optimism that accompanied the start of the Obama administration.

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The partisan and ideological divisions are as profound as would be expected in an election year - but with better results for Ryan among independents. They tilt positively on Ryan, 43-32 percent, favorable-unfavorable, in this poll, produced for ABC by Langer Research Associates. Biden is underwater among independents - 36 percent see him positively, 49 percent negatively.

Biden pushes back, though, among political moderates. He's +12 points on the favorable side in this group, while Ryan is -11.

Ryan's trajectory among partisan groups is telling: Among Republicans, he's gone from 48 percent favorable views before his selection to 62 percent right after it and 80 percent now - steady growth in his base. Among Democrats, though, it's his unfavorable rating that's grown, from 50 percent, to 58, and now to 72 percent. He showed initial improvement among independents; that flattened in the past week.

Divisions among other groups on Biden and Ryan largely reflect those on Obama and Romney at the top of the tickets. Ryan has a 15-point positive margin in favorability among seniors, apparently unperturbed by his proposal to restructure Medicare (starting in a decade), vs. an even split among young adults. Biden, by contrast, is +17 points among young adults, -11 among seniors.

Ryan is more popular among men (+11 points in favorability) than among women (-3), while Biden's ratings are similar in both groups. Among whites Ryan is +13 points in favorable vs. unfavorable ratings, while Biden is -11; among nonwhites, Ryan is -15 points, Biden +26.

There also are regional differences, largely reflecting partisan and ideological distributions. Ryan does much better (50-28 percent, favorable-unfavorable) in the more conservative and more Republican South than in his native Midwest (37-42 percent); Biden, in turn, is weakest in the South, and exceeds Ryan by 17 points in favorability in the Northeast.

Ryan has more room to move: Twenty-two percent are undecided about him, compared with 14 percent on Biden. But that's a shrinking difference; indecision on Ryan has been halved since his selection for the GOP ticket.

METHODOLOGY - This ABC News/Washington Post poll was conducted by landline and cell phone Aug. 15-19, 2012, among a random national sample of 1,020 adults. Results have a margin of sampling error of 4 points. The 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.