WASHINGTON — A season of surprises turned primarily to a fight between John Kerry and John Edwards on Tuesday — two candidates meeting deferred expectations at just the right time.

A month after it appeared that both men would fail in once-promising presidential candidacies and be buried by the high-flying Howard Dean, the two senators — Kerry from Massachusetts and Edwards from North Carolina — were the biggest winners in Democratic primary and caucus voting in seven states Tuesday.

Retired Gen. Wesley Clark hoped to remain viable with an extremely close edge over Edwards in Oklahoma and a second-place finish to Kerry in Arizona.

In 15 tough days of campaigning and voting, Kerry has proven to be the only Democrat with front-runner appeal across the map.

"For the second time in a few days, a New England patriot has won on the road," Kerry said, in remarks at his victory celebration in Washington state, comparing himself to the Super Bowl champions.

Edwards fulfilled, at least among Democrats, his frequent claim that the South was his "back yard," but he must still win consistently on unfamiliar turf to challenge Kerry's front-runner status. That test may come as early as Saturday in Michigan, but no later than Feb. 17 in Wisconsin.

"If the American people give me a shot at George Bush . . . this November, I will give them back the White House," Edwards told celebrating supporters in South Carolina.

Kerry tightened his front-runner grip with wins in Delaware, Arizona, North Dakota, New Mexico and Missouri, Tuesday's top delegate prize. With a convincing win in his home territory in South Carolina and a good finish in Oklahoma, Edwards emerged as Kerry's top challenger. Dean was beaten decisively again for the third straight week. Speaking to supporters in Washington state, he acknowledged that it was a "tough" night. But Dean vowed to "keep going and going and going and going" because "this is all about who gets the most delegates (at the Democratic National Convention) in Boston in July, and it is going to be us."

Still, Dean is on the precipice of irrelevance, a one-time front-runner with fewer places to run.

"It seems to me he is on life support," said Clemson University political scientist Bruce Ransom.

Kerry, as expected, capitalized on momentum from victories in Iowa and New Hampshire last month by winning convincingly in Missouri, a key swing state in the fall presidential election. Missouri had 74 of the 269 delegates up for grabs.