Jeb Bush and the far less well-known Rob Portman draw more negative than positive reviews as potential Republican vice presidential nominees, with challenges for Bush among moderates and swing-voting independents, and for Portman both among conservatives and within his own party.

Another potential candidate, Marco Rubio, fares better in the latest ABC News/Washington Post poll, albeit with just a split decision as Mitt Romney's 2012 running mate. Rubio receives more positive than negative responses among his fellow Hispanics, though with a third undecided.

See PDF with full results, charts and tables here.

Americans by 45-36 percent express an unfavorable rather than favorable opinion of Bush, the former Florida governor, for the slot, and by 30-19 percent say the same about Portman, the junior U.S. senator from Ohio. It's a closer 32-29 percent on Rubio, Florida's junior senator.

This poll, produced for ABC by Langer Research Associates, finds room to move, especially for Portman and Rubio: Large numbers, 51 percent and 39 percent respectively, have no opinion of them. That declines to 19 percent for Bush, better known through his governorship from 1999-2007 and his father's and brother's presidencies.

GROUPS - Notably, independents respond more unfavorably than favorably to the prospect of a Bush nomination for the vice presidency by a 10-point margin, 46-36 percent. Independents divide essentially evenly, by contrast, on Rubio and Portman alike. (Democrats and liberals are broadly negative on all three, but particularly so on Bush - who said this week he wouldn't take the slot if offered.)

Bush also is weak among moderates, who see his participation on the GOP ticket unfavorably rather than favorably by a broad 56-29 percent. Moderates divide more closely on Rubio (negative by a non-significant 6-point margin), and essentially evenly on Portman.

Portman, though, has his own difficulties: Republicans only split evenly on the prospect of his selection, 21-22 percent, favorable-unfavorable. That compares with a 44-point margin among Republicans in positive vs. negative responses to a Bush candidacy, and 32 percentage points for Rubio.

That in turn reflects a comparative weakness for Portman, who's generally known as a moderate, among conservatives. They respond more unfavorably than favorably to Portman for vice president by a 9-point margin, 26-17 percent. By contrast, conservatives respond more positively than negatively to Bush by 18 points and to Rubio by 15.

True to their partisan predispositions, Democrats and liberals see Bush negatively rather than positively for the nomination by 69-16 percent and 61-26 percent, respectively. Democrats side against Rubio by 50-16 percent and Portman by 46-14 percent; liberals against Rubio by 49-20 percent and against Portman by 44-21 percent.

As noted, Hispanics look favorably on a Rubio candidacy by 41-26 percent (with a third undecided), while dividing about evenly on Bush and Portman alike.

ALLOCATION - Another way to evaluate these results, given the high numbers with no opinion of Rubio and especially Portman, is to look at the numbers only among those who have an opinion - allocating the undecided proportionately to those who do have a view.

The story's similar; overall, among those with an opinion, negative views outnumber positive ones on Portman by 62-38 percent and on Bush by 56-44 percent, with a narrower 53-47 percent unfavorable-favorable split on Rubio.

By party, 77 percent of Republicans with an opinion respond favorably to Bush and Rubio alike, but this drops to 49 percent for Portman; and independents with an opinion divide about evenly on Portman and Rubio, but respond negatively to Bush by 57-43 percent.

Among ideological groups, moderates who have an opinion view Bush for vice president negatively rather than positively by 66-34 percent, while dividing more closely on Rubio and Portman. Conservatives with an opinion respond positively to Bush by 61-39 percent and to Rubio by a similar 62-38 percent - but negatively to Portman, 61-39 percent.

METHODOLOGY - This ABC News/Washington Post poll was conducted by landline and cell phone May 30-June 3, 2012, among a random national sample of 1,009 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.