WASHINGTON (AP) -- Hillary Rodham Clinton is the favorite right now for the Democratic nomination for president, but the party is a "lifetime" away from making its 2008 choice, one of her White House rivals said Sunday.

"I think she's incredibly formidable and has got to be the front-runner and the odds-on pick right now. But this is a marathon. There's a long way to go," said Sen. Joe Biden, D-Del.

The former first lady and current New York senator joined the race on Saturday, hoping to become the first female president. A crowded field of candidates is led by Clinton, Illinois Sen. Barack Obama and 2004 vice presidential nominee John Edwards. New Mexico Gov. Bill Richardson jumped in on Sunday. Biden, however, said he did not look at the race as Clinton's to lose.

"Look, listen, we're a lifetime away. Hillary Clinton is going to have to make her best case. And there's a lot of us out there that are known but in a sense not known, and we're going to make our best case. And I don't think Hillary's best case versus mine or Barack's or anybody else's necessarily trumps us," said Biden, chairman of the Senate Foreign Relations Committee.