A mash-up in Iowa confirmed deep intraparty fractures in the race to win the Republican nomination for president, leaving the top three finishers with some credit to claim, but also - and perhaps particularly Mitt Romney - with some impressive bruises.

While scoring heavily among caucus-goers most concerned with electability, Romney failed to improve on his 2008 showing in Iowa, did poorly with very conservative and evangelical voters, and flagged among those focused on the "true conservative" or the candidate with the strongest "moral character." He won Republican pragmatists, but not conservative true believers.

Rick Santorum took advantage of Romney's weak spots, winning evangelical and very conservative voters, and those focused on moral character, as well as late-deciders. One question is how well Santorum plays in states with fewer evangelicals participating; they accounted for a broad 58 percent in Iowa. Another is how well he withstands the new found scrutiny his showing is sure to bring.

Ron Paul, for his part, notched third place by scoring very strongly among independents who turned out in much bigger-than-usual numbers - a feat he won't be able to replicate in closed primaries - and young voters, whose turnout tends to be uncertain. The question is how well his anti-establishment candidacy plays in better-attended primaries, where highly motivated but small groups may wield less clout.

If these candidates' pile-up added little clarity to the top of the race, it raised the winnowing question - how long the more distant finishers can stay in the contest, and if they leave, where their supporters go.

The entrance poll was conducted for ABC News and its partner news organizations, and analyzed for ABC by Langer Research Associates. As noted, it found Santorum boosted by attendees who made their decision in just the last few days; they accounted for a broad 46 percent of participants, and he won 33 percent of them. He also won a third of very conservatives (more than double Romney's showing in this group), three in 10 strong supporters of the tea party movement and 32 percent of evangelicals.

Strikingly, 23 percent of caucus-goers identified themselves as independents, up from just 13 percent in 2008. Paul won a smashing 44 percent of them, improving on his performance among independents in 2008, when he won 30 percent of this then-smaller group. Indeed, 53 percent of Paul's supporters identified themselves as independents, or, a few, as Democrats - not as Republicans. Paul likewise won the roughly four in 10 Iowans who were attending their first caucus, many of them independents.

Seventy-six percent of Paul's supporters decided early - more than a few days ago - raising questions about his ability to draw fresh converts. By contrast, 64 percent of Santorum's supporters decided on him in just the last few days, a key quality if it plays elsewhere. On this Romney landed between the two.

Paul won 48 percent support among caucus-goers under 30, more than double his score in this group in 2008. But Romney scored much better among seniors, with 32 percent support - and, as often is the case, there were a lot more of them voting.

Romney also made back ground, particularly against Santorum, among non-evangelicals, with 38 percent support. Most notably, though, he won 49 percent of caucus-goers looking mainly for the candidate they thought was best able to beat Barack Obama. Beating Obama was a top candidate attribute, with three in 10 calling it the most important trait.

But other attributes worked less well for Romney. He and Newt Gingrich split those looking mainly for experience in a candidate, with 33 and 29 percent, respectively. And those looking chiefly for a "true conservative" divided between Paul and Santorum - a mere one percent in this group backed Romney, underscoring his challenges in the strongly conservative wing of the party.

Income differences were sharp as well: among the best-off caucus-goers, those with household incomes over $100,000, Romney finished first with 36 percent (and they were more numerous than in 2008). Among the less well-off, with incomes under $50,000, Romney plummeted to 15 percent support, vs. 31 percent for Paul. (Some of that, but not all of it, owes to his attraction to young voters, who tend to have lower incomes.)

Paul also had a true-believer edge: Seventy-three percent of his supporters "strongly" backed him, compared with 63 percent of Santorum's and 56 percent of Romney's. Strong support was up for Paul by 11 points from 2008 - but did not improve for Romney.

While the economy led the list of most important issues, cited by 42 percent, a significant number, 34 percent, said it was the federal budget deficit instead. And while Romney won economy voters, Paul prevailed among those more concerned with the deficit. Abortion was a far less-mentioned top issue, but among those who selected it, a thumping 57 percent picked Santorum, in keeping with his strong showing among evangelicals and very conservatives.

While each of these three candidates may take bragging rights from the results, it's notable, as mentioned, that Romney did less well among very conservatives - 14 percent support - than he did in 2008 - 23 percent. For every pragmatic caucus-goer seeking an experienced candidate who can win the general election, there was another looking for a true believer with strong moral fiber. In the latter group, Romney did not prevail.

Another question, though, is how well the Iowa caucuses themselves translate more broadly. Compared with all Republicans nationally, as well as the general public, there are some striking differences:

-Per the entrance poll, 83 percent of GOP caucus-goers identified themselves as conservatives, 47 percent as "very" conservative. That compares with 67 and 32 percent of all Republicans, and 37 and 16 percent of all Americans, in ABC News/Washington Post polling nationally.

-Fifty-eight percent of GOP caucus-goers in Iowa identified themselves as evangelicals. Among all Americans, it's 20 points lower, 38 percent.

-Ninety-nine percent of Iowa Republican caucus participants were white - compared with 86 percent of all Republicans nationally, and 77 percent of all adults.

The differences among Iowa GOP caucus-goers may help explain why, in the six contested Republican caucuses since 1976, the winner in Iowa went on to win the nomination in just three - Gerald Ford, Bob Dole and George W. Bush - and to win the presidency in just one.