Washington ? Massachusetts Sen. John Kerry lined up support from former rival Dick Gephardt on Thursday in an accelerating rush toward the Democratic presidential nomination. Howard Dean withdrew to Wisconsin for a defiant last stand.

“I never run away from anything, especially George Bush,” Kerry shot back at a heckler in Portland, Maine, one of three states he hopes to add to his campaign trophy case over the next few days.

Everywhere he went, Kerry’s path was cleared by establishment Democrats bearing fresh endorsements. Gov. John Baldacci and former Sen. George Mitchell from Maine climbed aboard the Kerry bandwagon during the day, as did Sens. Carl Levin and Debbie Stabenow from Michigan.

Officials said Gephardt would announce his support today in Warren, Mich. and that some of the 14 unions who backed the Missouri lawmaker’s own failed bid for the White House would soon follow.

That left Dean, Sen. John Edwards and retired Gen. Wesley Clark looking for spots to slow Kerry’s rush to the nomination.

The immediate campaign calendar held out the prospect of fresh momentum and scores of delegates for Kerry and discouragement for his pursuers.

None of his rivals has made a strong effort in Michigan or Washington, where caucuses on Saturday offer 204 delegates combined. Maine’s caucuses the next day have 24 delegates at stake.

It was a measure of Dean’s depleted prospects that he was making no apparent effort in Tennessee, the state that launched Al Gore’s political career. Gore’s endorsement in early December marked a major coup for the former Vermont governor, who at the time was trying to make the transition from an antiestablishment candidate to one who could draw party insiders to his side.

In an early morning e-mail to his supporters, Dean laid out his last-ditch strategy, coupling it with an appeal for campaign donations.

“We must win Wisconsin. … We will get a boost this weekend in Washington, Michigan, and Maine, but our true test will be the Wisconsin primary.

“A win there will carry us to the big states of March 2 and narrow the field to two candidates. Anything less will put us out of this race,” he wrote.