Richmond, Va. Democrat Mark R. Warner, the former governor of Virginia, has decided not to run for president in 2008, saying he wanted "a real life" and feared the effect of a drawn-out campaign on his family.
Warner, 51, would not rule out running for the Senate or seeking the governorship again; the state bars incumbents from seeking re-election.
Warner leaves a crowded field of possible Democratic candidates.
Sen. Hillary Rodham Clinton of New York is widely considered the front-runner for the nomination.
Others considering or positioning themselves for a run include Sen. John Kerry of Massachusetts, the 2004 Democratic nominee; former Sen. John Edwards of North Carolina, the vice presidential nominee two years ago; Sens. Evan Bayh of Indiana, Joe Biden of Delaware, Christopher Dodd of Connecticut, Russ Feingold of Wisconsin, Iowa Gov. Tom Vilsack and New Mexico Gov. Bill Richardson.