Kerry finished with 40 percent of the vote, Edwards had 34 percent, Dean 18 percent, Rep. Dennis Kucinich of Ohio 3 percent and Al Sharpton 2 percent.
Edwards said the results, which were closer than polls predicted, narrowed the race to a two-man affair. "We'll go full-throttle to the next group of states," he said, pledging to campaign in California, New York, Ohio and seven other states holding primaries or caucuses March 2. At stake will be 1,151 delegates, more than half the total needed to claim the nomination.
Dean told supporters he was ending his campaign on Wednesday, but still hoped to keep alive the issues that have fueled his candidacy.
"I am no longer actively pursuing the presidency," Dean told a cheering crowd in Burlington, Vt. "We will, however, continue to build a new organization using our enormous grass-roots network to continue the effort to transform the Democratic Party and to change our country."
There were reports Dean was considering endorsing one of his rivals, but no indication when he might make that decision.
Reacting to his narrow lead, Kerry said, "A win is a win." Despite his narrow victory, Kerry focused most of his victory speech on President Bush, reports CBS News Correspondent Byron Pitts.
"We reject the view that a president's job is just to raise the value of the stock market. We believe the job of a president is to put America back to work. And to do it now," Kerry said.
With Wisconsin, Kerry has won 15 of the 17 elections — seven by nearly half the vote — on the East and West coasts, in the Midwest, the Great Plains and the Southwest. He remains the undisputed frontrunner, flush with money and momentum heading toward three contests Feb. 24 in Utah, Idaho and Hawaii and then the delegate-rich elections March 2.
But the Edwards surprise ended any hope for a quick conclusion to the race and earlier-than-ever general election planning. A poor second-place showing would have crippled Edwards' campaign.
Counting Wisconsin, Kerry has pocketed 594 of the 2,161 delegates needed to secure the nomination, according to an analysis by The Associated Press. Dean had just 195, Edwards 179 and Sharpton 16.
Buoyed by his hot streak, Kerry took two days off last week and ignored his rivals in Wisconsin while focusing on Mr. Bush in hopes of persuading voters the nominating fight was over.
Kerry held a wide lead in pre-election polls, but the surveys did not fully reflect voter sentiments after a statewide debate Sunday, Edwards' criticism of Kerry's free-trade policies and two newspaper endorsements for Edwards.
"Not so fast, John Kerry," Edwards said in Sunday's debate, five words that may best sum up the impact of Tuesday's results. Exit polls show nearly half of those who voted for Edwards made up their minds in the last few days, attracted to his message on trade and the economy.
The polls also did not take into account 11th-hour criticism of Kerry from Mr. Bush's re-election team.
"We underwent a lot of Republican attacks the last week. Notwithstanding those attacks, we showed we can fight back," Kerry told the AP.
Edwards benefited from Wisconsin's open primary system. His breakout was fueled by the highest Republican turnout of the primary season.
According to CBS News exit polls, 29 percent of the voters who went to the polls were independents, and they supported Edwards over Kerry by a 41-27 percent margin.
Edwards did even better among the 10 percent of primary voters who identified themselves as Republicans, besting Kerry by a 45-18 percent margin. Primaries in Georgia, Ohio and Vermont on March 2 will be open to all voters as will the caucuses in Minnesota.
"It's obvious from the exit polling here in Wisconsin that I was much more appealing to independent voters and moderate Republicans, and we have to get these people to win the general election," Edwards told CBS News Anchor Dan Rather.
Dean ignored pleas to give up the fight. "We are not done," he told his supporters, even as his own advisers were saying his campaign for the presidency was effectively over.
Senior advisers, speaking on condition of anonymity, said Dean was considering dramatically scaling back his campaign with no hope of winning the presidency. He was just as likely to cede the nomination and, with hopes of becoming a kingmaker, endorsing a rival.
His campaign reached out to Edwards' team, knowing that Dean's fund-raising prowess could help reshape the race, aides said. But they did not rule out Dean endorsing Kerry, a move they said would seal the nomination for the Massachusetts lawmaker.
Edwards told the CBS News Early Show Dean has "made an enormous contribution to this campaign, bringing in lots of people who otherwise wouldn't have been involved, particularly young people."
Edwards called for a one-on-one debate with Kerry heading toward March 2.
Kerry plans to compete in every March 2 state, airing ads where Edwards is faring well in polls or buying TV time. Edwards intends to target Ohio, New York and Georgia, airing ads in upstate New York and large sections of the other two states.
First, he needs to raise money. Edward issued an e-mail appeal Tuesday, telling donors, "Every single contribution" counts.
Aides say Edwards' populist message will resonate in Ohio and upstate New York, areas hard hit by job losses. The Southern-bred candidate also should do well in Georgia. California is by far the day's biggest prize, with 370 delegates, followed by New York with 236.
"The guy is positive," said Edwards voter Bill Lohr, 50, of Sun Prairie, Wis., said. "He's got a good heart. Kind of like Bill Clinton got us rocking."
But Byron Conway, 27, of Milwaukee, said Kerry was the only candidate with a shot at beating Mr. Bush. "I just want him out," he said.