THE SELECTION of a Democratic nominee for president may be a "lifetime" away, as Delaware Sen. Joseph R. Biden Jr. puts it, but more and more hopefuls are jostling for position at the starting gate.

"This is a marathon," Biden said yesterday. "There's a long way to go."

The latest entrants over the weekend included the heavyweights, New York Sen. Hillary Rodham Clinton and Illinois Sen. Barack Obama. They are considered the most formidable of the half-dozen names tossed into the hat so far.

But New Mexico Gov. Bill Richardson, who announced yesterday and who has an extensive political resume, will be at least a light-heavy.

Then there are former Sen. John Edwards of North Carolina, the 2004 nominee for vice president; Biden himself; Christopher J. Dodd of Connecticut; former Gov. Tom Vilsack of Iowa; Rep. Dennis J. Kucinich of Ohio; and former Sen. Mike Gravel of Alaska.

How many others are waiting in the wings is not known at this time, but the electorate shouldn't be surprised by any new arrivals.

Clinton, the former first lady, announced her candidacy Saturday in a video posted on her Web site.

"I'm in," she said, "and I'm in to win."

She said she is forming an exploratory committee to test the waters, but made it clear she's not just sticking a toe in the tide.

"I want you to join me not just for the campaign," she said, "but for a conversation about the future of our country. And I am forming my exploratory committee because I believe that together we can bring the leadership that this country needs."

The potential candidates now include a woman (Clinton), an African-American (Obama) and a Hispanic (Richardson).

Former Republican House Speaker Newt Gingrich, who is considering his own run for the GOP nomination, speculated yesterday that Clinton was forced to show her hand weeks in advance by Obama's candidacy.

"I mean," Gingrich said on Fox News Sunday, "he has gained ground so rapidly that I think she sort of thought she had to remind her friends she was around."

Gingrich gave Clinton a "6-out-of-10 chance or better" of sewing up the nomination.

Biden, chairman of the Senate Foreign Relations Committee, said, "I think she's incredibly formidable and has got to be the front-runner and the odds-on pick right now."

"Look, listen, we're a lifetime away," he added.

Clinton, 59, is fresh from an easy re-election victory last November in the New York senatorial race. If she wins the presidency, she would be going home, in a sense. The White House was her abode for the eight years of the presidency of her husband, William Jefferson Clinton.

Among the reasons her candidacy is so formidable is the fact that she has $14 million in the bank, more experience in the national arena, and a battle-tested campaign staff.

However, some political strategists see the 45-year-old Obama as a "fresh face" who would not have the baggage other candidates might bring to the race.

Clinton, for instance, might still be tainted by the sex scandal that marred the final years of her husband's presidency.

One Democratic analyst, Katie Merrill, said that Obama "has created a wave that is compelling."

Richardson brings a vast array of experience to the contest. He served as a member of Congress, ambassador to the United Nations, energy secretary, and governor of New Mexico since 2002.

"I am taking this step because we have to repair the damage that's been done to our country over the last six years," he said in a statement.

He also is fresh from an easy re-election victory in November.

Looming over all candidates is the issue of Iraq. Clinton has been forced into the position of explaining her vote for the war. Obama was in the Illinois legislature when the vote was taken and has expressed his opposition to the war without a past taint.

In Clinton's announcement Saturday, she said the war has to be brought to "the right end."

Richardson said, "We must get our troops out of Iraq without delay," but he has called for a phased withdrawal.

"I know the Middle East well, and it's clear that our presence in Iraq isn't helping any longer," he said.

Another factor that could throw the presidential primary race into the proverbial cocked hat is the possibility that California will move its primary election from June to the first week in February.

Gov. Arnold Schwarzenegger and some legislators started a movement last week to make the move. The question would then be who would benefit from a change that would make California the most important primary state.

Some speculate that Obama's fresh face would appeal to the open-minded California voter. On the other hand, Bill Clinton did well in California and is still popular there.

"California is bigger and more open-minded than most other states," said Bill Carrick, a veteran Democratic consultant, "which gives a chance for somebody to walk in, like a Barack Obama."

But because of the size of the state and its diverse population, "name ID and money will be a big thing, and Hillary has both of those." *

Daily News wire services contributed to this report.