McCain won New Hampshire in 2000, also on the strength of support from independents. The question again is whether he can expand his support in states where fewer of them turn out.
McCain also benefited from a good showing in the recent debates: Among the four in 10 Republicans who said the debates were very important in their choice, he won 39 percent support to Romney's 31 percent. Perhaps as a consequence, McCain won by 41-31 percent among voters who decided in the past three days (including today).
On candidate qualities, people looking for the candidate who "says what he believes" broke 53-15 percent for McCain over Romney. Among those looking for the most experienced candidate, 51 percent voted for McCain, 35 percent for Romney.
By contrast, voters looking for a candidate who "shares my values" favored Romney, 38 to 22 percent for Huckabee, 16 percent for McCain and 12 percent for Ron Paul.
Republican voters also saw McCain as the candidate who would be the strongest leader (41 percent, vs. versus 29 percent for Romney). About as many, 43 percent, said he was the best qualified to be commander-in-chief, compared with 27 percent for Romney.
That weakness on "values," as well as among conservatives, are question marks for McCain moving ahead. So is the fact that 45 percent of McCain's own voters said they were supporting him "with reservations," vs. 33 percent of Romney's.
Evangelicals accounted for 23 percent of voters in New Hampshire, vs. 60 percent in Iowa. They also voted differently: McCain was surprisingly competitive in this group, Huckabee 28 percent, McCain 28, Romney 27, essentially a three-way dead heat. In Iowa, Huckabee won 46 percent of evangelicals, Romney 19, McCain just 10 percent.
Huckabee's dissimilar showing among born-again Christians in Iowa and New Hampshire suggests that he might not automatically expect evangelical support as the Republican campaign moves on. Either that -- or New Hampshire evangelicals are just different.
McCain ran particularly well among the best-educated voters, beating Romney by 41-32 percent among voters who with a college degree, about half of the GOP electorate.
Half of all Republican voters said the economy's in bad shape; in this group McCain beat Romney 42- 21 percent. Among the 49 percent who said the economy's in good shape, by contrast, Romney won by 8 points, 41-33 percent.
About three in 10 Republicans said the economy was the most important problem facing the country, the top-rated issue; McCain won them by 41-21 percent. He also beat Romney among voters most concerned about the war in Iraq, and about terrorism.
Romney came back among the quarter of Republicans who said immigration was the top issue, beating McCain by almost a 3-1 margin in this group. Similarly, among those who favor deporting illegal immigrants back to their home countries (half of all GOP voters), Romney beat McCain by 40-24 percent. However, among the three in 10 who felt illegal immigrants should be offered a chance at citizenship, McCain won by more than 3-1.
Republican voters divided on the hot-button issue of gay and lesbian civil unions. Among the 38 percent who supported civil unions, McCain won by 43-26 percent; he and Romney roughly split the vote among the 60 percent who oppose gay civil unions.
-Analysis by Rich Morin, with Gary Langer, Bob Shapiro, Claudia Deane, Peyton Craighill, Pat Moynihan and Brian Hartman.