Barack Obama beat Hillary Clinton in some of her core support groups, trounced her on electability and rode broad support from independents to victory in Wisconsin, while John McCain gained ground among conservatives in winning his party's primary.
Clinton struggled in her base groups -- barely winning white women, losing less-educated and lower-income voters -- while Obama swept up younger voters, winning those under 30 by one of his biggest margins yet.
He beat by Clinton by 31 points among independents in Wisconsin's open primary, as well as by 7 points among Democrats.
Although Wisconsin Democrats were least likely to say "electability" was the most important candidate attribute, they also identified Obama, not Clinton, as most likely to win in November, by 63-37 percent.
The winning attribute, meanwhile, was "change," and as usual Obama owned it, prevailing among those voters by 77-22 percent.
Clinton also came in for criticism on negative campaigning; 54 percent said she attacked unfairly; far fewer, 34 percent, said Obama did so. And while 82 percent said they'd be satisfied with Obama as the nominee, fewer, 68 percent, said that about Clinton.
Wisconsin was one of the least racially mixed states Obama's won; of those in his column where exit polls were conducted, only Utah, Iowa, and Connecticut were as predominantly white. (Obama won 91 percent of blacks, who accounted for 8 percent of voters in the Wisconsin Democratic primary.)
Indeed Clinton won white women by only a 5-point margin, 52-47 percent; she's done less well in this group only in four previous primaries, losing them in New Mexico and Obama's home state of Illinois, and splitting them in Utah and Iowa.
Obama, meanwhile, prevailed by a wide margin among men, 67-31 percent. His win among white men, 63-34 percent, was surpassed only in Utah.
Less-educated whites have been a core group for Clinton; in previous primaries combined she's won those who lack a college degree by 30 points, while Obama's won college-educated whites.
In Wisconsin, however, Obama won less-educated whites, 52-47 percent, while crushing Clinton among the better-educated. That is Obama's best showing among less-educated whites in any primary to date.
Income told a similar story: The two evenly divided white voters with household incomes under $50,000. Clinton previously failed to win whites at that income level only in Illinois, Utah, and New Mexico.
By age, the most striking result was Obama's huge victory among voters under 30; he won them by 70-26 percent. (He's done as well or better in this group only in Georgia, Utah and Virginia.)
Under 30s accounted for 16 percent of Wisconsin Democratic voters, up from 11 percent in 2004 and a bigger share than in most previous primaries this year.
He also won middle-aged voters by a better-than-usual margin, while majority support for Clinton was isolated to senior citizens (customarily her best group, but by less a margin in Wisconsin than in previous primaries).
Twenty-eight percent of Democratic voters were independents, and nearly one in 10 were Republicans taking advantage of the open primary rules to vote in the Democratic contest.
Turnout by both groups was about the same as in 2004.
On the Republican side, exit poll results indicated progress for McCain on the ideological front; he won conservatives, albeit by a narrow 48-44 percent; previously he'd won this group only in Maryland, New Jersey and New York (and split them in Illinois).
McCain won 39 percent of "very" conservative voters, his best showing in that group to date.
As usual, moderates carried him home; he won them by 70-25 percent.
McCain's improvement among conservatives, however, did not include evangelicals: Mike Huckabee, a Baptist minister, won them by 56-36 percent.
McCain's support among evangelicals was about average for him; he was helped by the fact that they accounted for many fewer GOP voters, 38 percent, than in the Southern states Huckabee has won.
There were other examples of McCain's continued challenges in the Republican base. Forty-two percent said he's "not conservative enough."
Voters by a wide margin were most attracted to a candidate who "shares my values," and Huckabee won them by 53-36 percent.
And Republicans who most strongly oppose abortion, saying it should be illegal in all cases, went for Huckabee by more than 2-1, 64-30 percent
At the same time McCain easily prevailed as the candidate most likely to improve U.S. relations with the rest of the world, and, by a 6-1 margin, as the one most likely to beat the Democratic nominee in the general election in November.