Mitt Romney romped in the Nevada caucuses with a leg up from his Mormon co-religionists, but also with winning margins across other faith groups - evangelicals included - and a knockout even among the very conservative voters with whom he's struggled elsewhere.

His calling card: defeating Barack Obama. In this entrance poll, analyzed for ABC by Langer Research Associates, more than four in 10 caucus-goers named it as the most important candidate attribute in their vote, and those who did backed Romney by a smashing 74-18 percent over Newt Gingrich. That's Romney's best to date among beat-Obama voters.

Romney's rough spots on this cruise were few, but notable. He was crushed among the truest of the true conservatives, the 17 percent of caucus-goers who said they cared most about the candidate with the best conservative credentials. Forty-five percent in this group supported Ron Paul, 31 percent Gingrich, 19 percent Rick Santorum - leaving a mere 5 percent for Romney.

He also lost self-identified independents to Paul, ran only about evenly with Paul among voters under age 30, split those with incomes under $30,000 a year and won strong supporters of the Tea Party political movement much more narrowly than other groups, by 9 points over Gingrich.

Still, Romney overachieved essentially everywhere else, and in much larger groups - albeit in what by any standard was a lightly attended event (only about 50,000 voters were expected), and in a state in which he won easily, with 51 percent of the vote, in 2008.

Mormons made up 26 percent of caucus participants Saturday, about the same as their share in Nevada in 2008 and far more than in previous contests this year. Ninety-one percent of them voted for Romney; Mormons accounted for more than four in 10 of his total votes.

But Romney also easily outpaced Gingrich among evangelicals, 45-29 percent, his best showing by far in this group to date. As such it was essentially inconsequential that, at 27 percent of the electorate, evangelicals were much less numerous than in most previous 2012 Republican events. They accounted for 65 percent, 57 percent, and 47 percent in South Carolina, Iowa and Florida, respectively.

While light on evangelicals, Nevada was rich in "very" conservatives, 48 percent of caucus-goers, rivaled only in Iowa. As with evangelicals, Romney has struggled among very conservatives elsewhere, losing them in all previous contests save New Hampshire. He won them in Nevada by 2-1 over Gingrich.

And while Romney got hammered among the one in six looking mainly for a "true conservative," he stormed back among other groups. In addition to the big beat-Obama vote, he beat Gingrich by 23 points among voters looking for the candidate with the best experience, and Paul by 23 points among those focused on "strong moral character." The latter group, one in five voters, has been a weak one for the thrice-married Gingrich.

Gingrich and Paul battled for second place. Paul won self-identified independents, consistently a better group for him, by 48 percent to 31 percent over Romney; Paul's misfortune was that independents accounted for just 18 percent of voters in the caucuses, which were open only to registered Republicans.

Paul and Romney were even among voters under age 30, but they accounted for just 8 percent of the turnout. Seniors, customarily a strong Romney group, accounted for 35 percent of caucus-goers, and backed him over Gingrich by 59 percent to 25 percent, with just 11 percent for Paul.

Among income groups, voters with household incomes less than $30,000 a year split three ways among Romney, Gingrich and Paul - but made up just 10 percent of Nevada voters. Romney won 48 percent of those in the $30,000 to $50,000 range, and 60 percent of those better off.

While Romney won strong Tea Party supporters by just 9 points, that itself was a major improvement from the previous two GOP contests. He lost this group to Gingrich by 12 points in Florida, and by 27 points in South Carolina.

A challenge for Gingrich was the narrow base of his support: Six in 10 of his voters were very conservatives, and two-thirds were strong Tea Party supporters. Paul, in turn, got 44 percent of his support from independents - a tough profile for a Republican candidate.

Finally, entrance poll results indicated that Romney did particularly well in Clark County, home to Las Vegas and more than half of all caucus-goers. He did similarly well in Clark County in 2008, but this year that score might be a particular message to Gingrich, whose most prominent financial backer, casino magnate Sheldon Adelson, calls Las Vegas home.