As Gore steps aside, Democrats vie to wear his shoes.

Byline: Mark Silva

WASHINGTON _ The gathering storm over Iraq isn't the only conflict President Bush faces. Two years out, a suddenly emboldened field is forming to contest his re-election.

With Democrat Al Gore's announcement that he will not seek his party's nomination for president in 2004, at least a half-dozen other Democrats now face clear paths for their own campaigns.

The Republican president may be popular _ more popular than the average midterm president, his standing buoyed by support for his handling of an unprecedented war. But two years is a lifetime in national politics, and the withdrawal of the Democratic Party's 2000 nominee breathes new life into the prospects of the party's most ambitious leaders.

One's already running: A friendly if little-known physician named Howard Dean who has logged a decade as governor of Vermont.

The senator from Massachusetts with a JFK monogram _ John Forbes Kerry _ has opened an exploratory campaign and already staked out first place in New Hampshire's first-in-the-nation primary. Connecticut Sen. Joseph Lieberman, Gore's running mate in 2000, now has the green light he awaited for his own campaign.

Without Gore in the contest, a fresh poll of likely Democratic voters in the earliest primary and caucus states shows, Kerry holds a strengthened, if early, lead over other Democrats in New Hampshire. And U.S. Rep. Dick Gephardt, the Missouri Democrat who stepped aside as House Minority Leader after his party suffered sweeping defeats in November, becomes the…