FAIRFAX, Va. — John Kerry cemented his position as the Democratic front-runner Tuesday with twin wallops in Virginia and Tennessee that he said proved he could win "East, West, North, and, now in the South."

"We will fight for every vote and we will carry our cause all across this land," Kerry said in a speech at George Mason University.

Kerry pledged to take it "one step at a time," first sealing up the nomination and then targeting President George W. Bush.

"People want change in the country," the Massachusetts senator told The Associated Press. "They want to move forward in a new direction, and I think I'm articulating what that new direction can be. It's crossing all lines ... without regard to region and other labels."

Kerry, labelled a liberal by Republican foes, called his victories an example of his cross-country appeal. Kerry blew away two Dixie-bred rivals, John Edwards of North Carolina and Wesley Clark of Arkansas.

"What we showed today is the mainstream values that I've been talking about, fairness and hope and hard work and love of country, are more important than boundaries and birthplace," Kerry said.

Kerry tapped into voter anger and dissatisfaction with Bush, especially among those eager to win in November, according to Associated Press exit polls.

He ran very strong among those who said the most important candidate quality was the ability to defeat Bush - claiming three-fourths of the Virginia voters who said that quality was most important and almost two-thirds of Tennessee voters who wanted to support a general election winner.

"Once again, the message rings out loud and clear," Kerry said. "Americans are voting for change - East and West, North, and, now in the South."

Bolstered by the confidence of winning 12 of 14 primary contests, Kerry planned a couple days of rest, nursing a cough and working the phones from home in Washington. Then he campaigns in Nevada, which holds caucuses Saturday, and Wisconsin, where his opponents are awaiting a showdown Tuesday.

"I'm on to Wisconsin," he said. "I think the campaign moves forward, and I'm going to continue to fight for every vote."

He said it's not up to him to decide whether his rivals should drop out, and he declined to say what message Bush should take from his victorious Tuesday.

"I think it would be presumptuous for me to make that determination. I'm just trying to focus on winning the nomination, and you take it one step at a time," Kerry said. "I've said that each time. I'm on to Wisconsin and I'm on to Nevada."