Rivals are trying to dent the perception that John Kerry (search) is solidifying his front-running campaign but face fresh evidence from both sides of the political aisle that Kerry's status is growing.

Kerry began Saturday in Las Vegas, where Nevada's state caucuses were under way. He spent the night at the Mandalay Bay Casino Hotel (search) but said he hadn't done any gambling. "I am gambling today" with the caucuses, Kerry said.

Asked his confidence level going into the caucuses, the front-runner said: "I am always hopeful. You always remain cautiously optimistic. I like the word cautious."

The Democrats plunged into the final weekend before the Wisconsin primary with both Howard Dean (search) and John Edwards (search) hungry for a win to revive their campaigns. Polls offered them little hope.

At a breakfast sponsored by black ministers, however, Dean showed no signs of discouragement. To an audience of more than 200, he said he had bolstered his campaign by turning to traditional Democratic voters.

"We're going to start with the African-American community. We're going to start with women," he said. "I'm tired of being divided in this country ... by race, by gender, by income or by religion."

Dean brought two guests to the breakfast, black roommates from his university days at Yale. One, Atlanta attorney Don Roman, sang a hymn to the group that asked: "Why should I feel discouraged?"

Kerry, who was flying to Milwaukee from Las Vegas, and Edwards headed to a big fund-raising dinner Saturday night in Milwaukee, and all major candidates planned to join a high-profile campaign debate Sunday, also in Milwaukee. Ohio Rep. Dennis Kucinich (search) was joining the dinner, and activist Al Sharpton (search) planned to join the debate.

Kucinich was out early Saturday, firing up about 200 people in Green Bay, north of Milwaukee. He took jabs at multilateral U.S. trade agreements, promised to provide universal health care and said: "I'm the only person running for president who has a plan to bring our troops home."

As his rivals scrambled, Kerry was targeted for individual attention from the Bush-Cheney Republican campaign, which distributed an attack video linking Kerry to special interests. Launching that on the Internet limited its audience, but it generated big media attention that magnified its impact.

Kerry treated the assault as more evidence that Republicans view him as the front-runner, arguing dismissively, "These guys will try to do anything to change the subject."

The Democratic front-runner made his campaign rounds Friday while repeatedly denying having had an extramarital affair. "I just deny it categorically. It's rumor. It's untrue. And that's the last time I intend to" respond to questions about it, he told reporters who asked about reports on an Internet site.

Adding to his momentum, the 13 million-member AFL-CIO announced plans to endorse Kerry next week, a sign that a linchpin of the Democratic Party considers the nomination all but settled.

The 64-union federation is eager to end the primary season so it can focus its resources and energy on defeating President Bush. While the candidates were focused on Wisconsin and the 72 delegates at stake there Tuesday, activists in Nevada and the District of Columbia were holding caucuses with 40 delegates are up for grabs.

On the trail, Kerry was joined by retired Gen. Wesley Clark, who offered his endorsement after ending his own campaign earlier in the week.

"Request permission to come aboard; the Army's here," said Clark, a reference to Kerry's service as a Naval officer during the Vietnam War.

As the primary season unfolds and Kerry builds momentum, increased attention is being given to delegates won by the major contenders. An Associated Press tally found that Kerry has claimed 539 delegates, compared to 182 for Dean and 166 for Edwards. It takes 2,161 delegates to win the nomination, and Kerry was certain to add to his count in the weekend tests.

Dean and Edwards are offering very different views of what happens to the Democratic race after Tuesday's primary, if they don't pull off an upset that could slow the front-running Kerry's momentum.

Dean once said it would be over if he lost Wisconsin but later modified that position to hold out the possibility he might press on. In his latest version, Dean said he simply didn't know what would happen to his campaign if he lost, but he talked as if he already had.

"I'm going to have to go to Burlington and figure out how to tackle 10 of the biggest states in America," said Dean. Pressed on his plans, Dean retorted: "I think it's a little early to be writing post-mortems."

Edwards, who has managed to win only in his birth state of South Carolina, offers a much more upbeat prediction of his future. He's prepared to push forward, he said.

"First of all, the nomination process is going to go on for a while, well into March," said Edwards.

He is diverting repeatedly from campaigning to raise campaign cash, and aides said he was in solid enough shape to continue. They said Edwards has raised $3.3 million since finishing second in Iowa's leadoff caucuses, including $500,000 he was expecting to raise at two events in Los Angeles Friday night.