Analysis from ABC News’ Gary Langer ( @langerresearch):

Barack Obama’s basic popularity has slipped to its lowest of his presidency, but his top two Republican challengers are no better off:  Rick Perry and Mitt Romney are far less known than Obama – and at least as divisive as he is among those who do have an opinion of them.

The result of this ABC News/Washington Post poll underscores the long road Perry and Romney face in making an impression on would-be voters – and their challenges in doing so. Perry, notably, is seen more unfavorably than favorably among Americans who’ve formed an opinion of him, and Romney manages only a split decision, much like Obama.

This survey, produced for ABC News by Langer Research Associates, is the first of a new series measuring the number of Americans who express a favorable or unfavorable impression of individuals in the news. Such ratings are the most basic measure of a public figure’s popularity.

On Obama, Americans now divide: Forty-seven percent see him favorably overall, fewer than half for the first time in ABC/Post polling since he announced his candidacy in February 2007 and down dramatically from his extraordinary peak, 79 percent, days before he took office in January 2009. Essentially as many adults now see Obama unfavorably, 46 percent, as favorably.

Read the full poll results.

Yet Perry, the Texas governor and Republican presidential candidate, has hurdles of his own. Thirty-one percent of Americans have an unfavorable opinion of Perry overall, exceeding the 23 percent who see him favorably. That’s marked by a shortfall in the political center: Independents, the keystone of national politics, see him more unfavorably than favorably by a 13-point margin.

Customarily it’s a trouble sign for a political figure’s unfavorable rating to exceed his or her favorable score. What helps Perry is the very large number of adults – 46 percent – who’ve yet to form an opinion of him one way or the other. Perry also has an advantage in the Republican base – greater strength of support than Romney’s among conservative Republicans and among Americans who call themselves “very” conservative.

Romney, for his part, has a 33-31 percent favorable-unfavorable rating, splitting the country much as Obama does, simply with opposite partisan divisions. Again, a very substantial number, 37 percent, have yet to form an opinion of Romney, despite his unsuccessful campaign for the GOP presidential nomination four years ago.

The high number who are undecided about Perry and Romney may in part reflect the fact that these views were asked without any preceding questions on politics or election preferences; as such they’re a particularly clean measure, taken with no possibility of priming.

To one extent, high undecideds represent an advantage for Perry and Romney alike; it’s generally easier to influence a decision that’s in the process of being made than it is to change an opinion once formed. Better then to have 31 percent unfavorable ratings, as Perry and Romney do, than 46 percent unfavorable, as Obama does. On the other hand, though, Obama has a favorable rating that’s 14 points higher than Romney’s, and double Perry’s – money in the bank, if Obama can hold on to it.

Another way to assess these ratings is to percentage them only among individuals who have an opinion, implicitly allocating those who are undecided proportionally to those who have an opinion. Just among Americans who have an opinion of Perry, 42 percent see him favorably, 58 percent unfavorably. For Romney and Obama it’s closer, 51-49 percent for both.

DIVISIONS – Naturally there are vast partisan and ideological divisions in these attitudes. Seventy-eight percent of Democrats see Obama favorably, reflecting continued strength in his base, albeit diminished from its peak. That slides to 42 percent among independents, and a mere 17 percent among Republicans. Similarly, Obama progresses from 76 percent favorability among liberals to a sharply lower 47 percent among moderates, 36 percent among “somewhat” conservatives and 21 percent among those who call themselves “very” conservative.

Both Perry and Romney have disproportionately favorable ratings among Republicans and conservatives. The difference is in the middle. Perry, as noted, is rated negatively on favorability among independents (by 23-36 percent) and also among moderates (by 17-32 percent). Romney does better in the middle – 35-30 percent among independents, 34-28 percent among moderates.

Favorable-unfavorable ratings

Obama    Perry    Romney

Democrats                               78-19%   12-44    20-43

Republicans                             17-80    43-11    55-19

Independents                         42-48    23-36    35-30

Liberals                                     76-18    11-50    20-45

Moderates                                 47-45    17-32    34-28

Somewhat conservatives    36-60    32-22    41-27

Very conservatives              21-76    52-18    48-26

Liberal Democrats                  86-10     7-55    17-53

Conservative Republicans  10-88     55-7    57-17

There are other differences among groups. Perry’s seen 10 points more favorably by men than by women; Romney, 16 points more favorably by senior citizens than by young adults. Romney has much higher favorability among college graduates (45 percent) than among non-graduates (27 percent), and does 20 points better among higher-income Americans than among those with incomes of $50,000 or less.

Obama is strongest in the West, and has maintained substantial favorability among Hispanics (61 percent) as well as among African-Americans (86 percent). Among whites, though, just 36 percent see Obama favorably, no better than Romney’s 38 percent – despite Romney’s being so much less well known.

INTENSITY – Finally, there’s the question of intensity – which overall doesn’t work well for any of these three. Obama’s seen “strongly” unfavorably by more Americans than see him strongly favorably, 31 percent vs. 22 percent. His strongly favorable rating is down by 11 points since spring.

But it’s the same 9-point margin for Romney – 14 percent strongly unfavorable vs. 5 percent strongly favorable. And Perry’s ratings are more strongly negative by 12 points, 19 percent vs. 7 percent.

Still, a difference in intensity emerges that gives Perry an advantage in two core GOP groups, conservative Republicans and Americans who call themselves very conservative. Conservative Republicans see Perry strongly favorably rather than strongly unfavorably by a broad 22-3 percent; for Romney, though, it’s 13-17 percent. And among very conservative Americans, the comparable numbers are 26-10 percent for Perry, vs. 12-13 percent for Romney. That positions Perry better in the Republican base – despite his greater challenges in the political center.

METHODOLOGY – This ABC News/Washington Post poll was conducted by landline and cell phone Sept. 14-18, 2011, among a random national sample of 1,013 adults. Results have a margin of sampling error of 3.5 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.

ABC News polls can be found at ABCNEWS.com at http://abcnews.com/pollingunit.