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With miles to go before they’re well known, Michele Bachmann and Ron Paul so far have struggled only to about an even split in public regard — with particular problems for Paul among some of the core Republican groups likely to be crucial in the party’s presidential contest.

All told, Americans in this ABC News/Washington Post poll divide by 27 percent to 31 percent in overall favorable vs. unfavorable impressions of Bachmann, and by a similar 25 percent to 27 percent on Paul — far from strongly positive ratings, although marked by the large numbers who’ve yet to form an impression of either candidate.

Among Republicans and very conservative adults, though, Paul has the greater challenges. While Republicans divide by 55 percent to 16 percent in favorable/unfavorable views of Bachmann, it’s a much closer 39-27 split for Paul — 16 points lower than Bachmann on favorability, 11 points higher on unfavorability, in their own party.

The gap between Bachmann and Paul also is wide among self-described “very conservative” Republicans: They divide by 66 percent to 13 percent favorable/unfavorable on Bachmann, but 47 percent to 29 percent on Paul — 19 points lower for Paul on favorability in this key GOP group, and 16 points higher on unfavorability.

Paul, a congressman associated with the libertarian wing of the Republican Party, makes back some of that ground in nontraditional areas for a Republican, with, for example, positive ratings at 22 percent among liberals, vs. Bachman’s 14 percent. But with liberals a small sliver of the Republican Party, Bachmann’s advantage among core Republican constituencies is more of an advantage in the primary season. (In another example, Paul’s unfavorability rating among Democrats is 14 points lower than Bachmann’s.)

Bachmann, though, has a weakness of her own — a notably unfavorable rating among college-educated adults, who are more reliable voters. Unfavorable views of Bachmann jump to 45 percent among college graduates, vs. 25 percent among non-graduates. (Non-graduates are much less likely to have formed an opinion of her.). Paul, by contrast, scores proportionately about the same among graduates and non-graduates alike.

Favorability is the most basic measure of a public figure’s popularity. ABC and the Post will be tracking these ratings across a variety of individuals and entities throughout the next year, with ABC’s participation in the project directed by Langer Research Associates of New York.

Paul and Bachmann have trailed Republican candidates Rick Perry and Mitt Romney in most recent surveys; ABC/Post results last week compared Perry and Romney’s favorability ratings (23-31 percent for Perry, with, notably, more unfavorable than favorable; and 33-31 percent for Romney) as well as Barack Obama’s (47-46 percent). All engender sharp divisions, underscoring the public’s stark political and ideological lines.

An obvious difference is in how well they’re known: For all his time on the campaign trail, 49 percent of Americans have yet to form an opinion of Paul, and nearly as many, 43 percent, have no impression of Bachmann. It was a similar 46 percent for Perry in last week’s results, and a lower but still substantial 37 percent for Romney, who first sought the GOP nomination in 2008. Far fewer have no opinion of Obama — an advantage for his challengers if they can turn popularity their way; a risk if undecideds turn against them.

METHODOLOGY: This ABC News/Washington Post poll was conducted by landline and cell phone Sept. 21-25, 2011, among a random national sample of 1,004 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.