Clark said in a broadcast interview that he expected to do well in contests in Tennessee and Virginia on Tuesday, and in Wisconsin on Feb. 17. But even if he didn't win in any of those states, Clark pledged to remain in the race at least through the March 2 "Super Tuesday" primaries, including in California, Ohio and New York.
"We've got a lot of support across this country," said Clark, a retired Army general. "We do expect to go on and do expect to be there on Super Tuesday."
In separate broadcast interviews, Edwards noted that some 75 percent of delegates to the Democratic National Convention will be up for grabs after the Wisconsin primary.
"I view this very much as a long-term process, and we're in this for the long term," said Edwards, adding that he also expected to do well in Tennessee and Virginia.
Former Vermont Gov. Howard Dean has said he must win Wisconsin to remain in the race, but the latest polls show Kerry comfortably ahead in that state, as well as in Tennessee and Virginia.
Dean said Kerry has a long way to go to clinch the nomination.
"I don't think Democrats are ready to choose just yet," Dean said Sunday in a broadcast interview. "With 15 percent of the delegates selected, that is not exactly a mandate."
Dean had his best showing of the campaign season on Saturday. He finished second in Washington with 30 percent of the vote and was battling for runner-up status in Michigan. But that was cold comfort for the former Vermont governor, whose once promising campaign unraveled further when the head of a major union withdrew his support.
Democratic officials said Gerald McEntee, head of the American Federation of State, County and Municipal Employees, delivered the news to the former front-runner during a meeting in Burlington, Vermont. It was a fresh blow for Dean, who has been shut-out in the primary season to date.
Clark and Edwards both largely overlooked contests this weekend to focus on Tennessee and Virginia, where they have been campaigning hard in hopes of emerging as Kerry's primary rival.
Kerry, the Democratic front-runner, has won nine of 11 primaries and caucuses held to date, losing only South Carolina to Edwards and Oklahoma to Clark.
The Massachusetts senator won caucuses Saturday with 49 percent of the vote in Washington state, and with 52 percent of the vote in Michigan.
Turnout in Washington state and Michigan was described as heavy Saturday.
CBS News Correspondent Cynthia Bowers says, "That so many voters showed up in two caucuses that were all but determined should fire a warning shot across the bow of the Republican Party that these voters will be back come November."
Maine, with 24 delegates at stake, was holding Democratic caucuses on Sunday.
Kerry was campaigning in Virginia on Sunday, where he was to pick up his latest endorsement, from Gov. Mark Warner. Edwards was making the rounds of Baptist churches in Richmond, Va., and attending a Democratic dinner in Nashville, Tenn. Clark was en route to Racine, Wis., to participate in a jobs forum before heading for the Nashville dinner. Dean was spending the day in Maine.