Exit Polls: Obama Makes Big Gains in Clinton's Core Support

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.

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Young Voters Strike

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.

McCain Makes Conservative Progress

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.