The contest now becomes a two-man affair, as Kerry and Edwards prepare to face off in two weeks on the biggest primary day of the year, when 10 states, including California, New York, Ohio and Maryland, cast "Super Tuesday" votes.
Howard Dean finished a distant third, effectively ending a presidential candidacy that rose and fell more spectacularly than any in recent history. Dean's remarks last night left little doubt that he knows his campaign is over, with a formal withdrawal announcement expected soon.
Kerry is still strongly favored to become the nominee, but Edwards emerged from Wisconsin with his status enhanced as the only real challenger left in the race.
Last night, Kerry appeared unruffled by his close call in a state where polls had showed him leading by more than 30 percentage points just a few days ago.
"Every week across our country, wherever we go, we're feeling the power of change that is sweeping across this nation," the Massachusetts senator told backers at a victory celebration outside Madison, the Wisconsin capital.
In a nod to voter anger over the outsourcing of American jobs, an issue that seemed to help Edwards here, Kerry vowed to "outsource George Bush's unaffordable tax cut for the wealthiest Americans, so we can invest in health care and education in this country."
Edwards, exultant over his stunning surge, which he said surprised even him, delivered a bold warning to the front-runner: "The voters of Wisconsin," he boasted, had "sent a clear message: ... 'Objects in your mirror may be closer than they appear.'"
Dean, meantime, was able to poke fun at himself, referring in what might well have been his last election-night speech to another disastrous election night -- in Iowa, just one month ago -- that sealed his doom as a presidential contender.
"You all make me so happy I could just scream," a smiling Dean told supporters at a Madison hotel.
His post-election remarks had a valedictory air, with Dean thanking those labor union supporters who hadn't deserted him for "sticking with us right to the end." One of his major labor backers, the public employees union, withdrew its support earlier this month.
Repeatedly, Dean told the crowd that "we are not done yet." But those remarks more likely referred to his plans to create a new, longer-range political movement rather than his intention to pursue a futile nomination quest.
Kerry, who had been expected to win easily, was forced to make a last-minute round of campaigning around Madison after early exit poll data suggested a tighter-than-expected finish.
"We really don't take anything for granted," he told CNN shortly before the polls closed. "You have to work for every vote."
But, Kerry added, "I want to make it clear that I am the strongest candidate to take on George Bush. ... We need a nominee of our party who has the ability to stand up to him and go toe-to-toe."
Edwards, who had been in single digits in Wisconsin polling 10 days before the primary, wound up with roughly one-third of the vote. The North Carolina senator said a two-person race with Kerry, which effectively begins today, was "the moment I've been looking for."
In an interview on CNN's Larry King Live, the North Carolina senator said there were "real differences" between him and Kerry.
Speaking from Milwaukee, Edwards said he offered voters "somebody who comes from them, who understands the problems that they have in their lives, who understands what the loss of a job means, who has the trade policy and tax policy that will work for all Americans, and not just the privileged few."
Edward was helped by the state's election law, which allows any registered voter to participate in the Democratic primary. According to an election-day survey of voters as they left their polling places, Edwards' strongest support came from voters in the Republican-leaning suburbs of Milwaukee, the state's largest city.
One in 10 voters was a Republican, and half of them chose Edwards, the exit poll found. By contrast, Kerry ran about 20 percentage points ahead of Edwards among self-identified Democrats.
Kerry plans campaign stops today in Ohio, a major industrial state that holds its primary a week from next Tuesday. Only one of the Super Tuesday states, Georgia, is in southerner Edwards' home region. Edwards is also targeting Ohio, which might be receptive to his protectionist trade message, as Wisconsin was.
Kerry continued to ride the momentum of his earlier victories, as those who voted for him yesterday repeated the pattern of earlier primaries.
His perceived electability made the difference in the election, the exit poll found. Half his voters said Kerry's potential to defeat President Bush was the main reason they supported him, rather than his position on issues.
By contrast, more than two out of three Edwards voters said they backed him because of his views, rather than an ability to defeat Bush. Edwards made his opposition to free trade a centerpiece of his campaign in this state, which has suffered a significant drain of manufacturing jobs.
Kerry, by winning his 15th of 17 primaries and caucuses, has expanded what was already a commanding edge in convention delegates. But most states have yet to vote and, even if he continues his dominance in the March 2 primaries, it will take weeks to cinch the nomination.
Catching him will be extremely difficult, however, even if Edwards can manage to halt Kerry's momentum. Democrats award national convention delegates on a proportional basis, which effectively guarantees Kerry continuing delegate gains, even in states where he doesn't finish first.
It seems clear, though, that Edwards has been generating excitement on the stump. Three-quarters of those who voted for him yesterday said they had made their decision within three days of the election, according to the exit poll.
During that period, Edwards received endorsements from two of the state's leading newspapers, in Milwaukee and Madison. The candidates also met in a televised debate Sunday night, when Kerry chose to play it safe while Edwards pointed up their differences on trade.
Edwards appeared to benefit from the pullout of retired Gen. Wesley K. Clark, even though Clark endorsed Kerry. With Dean a diminishing factor, some of his support might also flow to Edwards, who, like Clark and Dean, portrays himself as an outsider.
Dean entered the year as the favorite to capture the nomination. But Democrats cooled on him before the first votes were cast, and he was never could bounce back.
Dean returned to Burlington, Vt., last night. He is to meet with advisers and then announce his plans, perhaps as early as today.
The former Vermont governor is likely to convert his campaign, and its hundreds of thousands of diehard supporters, into a new post-campaign organization, his advisers say.
Kerry, eager to gain the support of former Dean backers if he becomes the nominee, was careful last night not to push his defeated rival from the race.
The timing of Dean's exit is "not my decision," Kerry said on CNN. "I have great respect for what Howard Dean has done and accomplished in this race."
Kerry stumped yesterday with his Massachusetts colleague, Sen. Edward M. Kennedy. In 1960, a victory by John F. Kennedy in the Wisconsin primary helped him secure the nomination. Edward Kennedy urged Wisconsin voters to "do for [Kerry] what you did for my brother."
DEMOCRATIC RACES AT A GLANCE
WHAT IT MEANS
Winning 15 out of 17 is a mighty feat in any league. But closer than expected Wisconsin finish says the race isn't over yet.
Super Tuesday campaign starts today. Ten states. Two Weeks. One front-runner.
WHAT IT MEANS
Primary voters don't want race to end. Southern senator is last man standing against Big John.
Do the math. More primary wins needed, pronto, or Kerry won't be stoppable.
WHAT IT MEANS
Call it HOward's end or Dean's Demise, bottom lin is the same. The jig is up, Doc.
Graceful election night speech shows he gets it. Next phase begins soon with launch of new reform organization.
Two left-wingers left in the race, Al Sharpton and Dennis Kucinich give Kerry cover ... They make Massachusetts liberal look more moderate and protect him from one-on-one debate with silver-tongued Edwards.
John Kerry ---- 40%
John Edwards --- 34%
Howard Dean --- 18%
99% PRECINCTS REPORTING
3,524 of 3,528 precincts - 99%
Candidate ............ Votes .......... %
John Kerry ........ 327,245 ........40%
John Edwards ... 282,978 ........34%
Howard Dean ..... 150,501 .......18%
Dennis Kucinich .. 27,215 ........ 3%
Al Sharpton .......... 14,647 ........ 2%
Candidate .................Earned in Wisconsin ..... Total to date
John Kerry ........................... 30 ............................. 460
John Edwards ....................... 24 ............................. 157
Howard Dean ......................... 13 ............................. 104
Wesley Clark * ......................... 0 ............................... 67
Al Sharpton .............................. 0 .............................. 12
Dennis Kucinich ...................... 0 ................................. 0
A total of 2,162 delegates are needed to win the nomination
* dropped out of race.