Warner scheduled a late morning news conference in Richmond to make the announcement. In a written statement, he said he made the decision after celebrating his father's 81st birthday and taking his oldest daughter, Madison, on a college tour.
"I know these moments are never going to come again," Warner said. "This weekend made clear what I'd been thinking about for many weeks — that while politically this appears to be the right time for me to take the plunge, at this point I want to have a real life.
"And while the chance may never come again, I shouldn't move forward unless I'm willing to put everything else in my life on the back burner," he said.
Since Warner left the governor's office in January, he has busily toured key states in the Democratic nomination process, including New Hampshire and Iowa.
New Hampshire Democratic Party Chairwoman Kathy Sullivan reacted saying she was "surprised" by Warner's decision.
"He had shown every sign of being a serious contender in New Hampshire. People liked him. He had gotten an excellent response up here," Sullivan noted.
Warner's political action committee, Alexandria-based Forward Together, has raised money for Warner's exploratory effort and for other Democratic candidates in this year's midterm elections.
"This is not a choice that was made based on whether I would win or lose," Warner said in his statement. "I can say with complete conviction that 15 months out from the first nomination contests, I feel we would have had as good a shot to be successful as any potential candidate in the field."
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.
Warner, a centrist who had won in a Republican-leaning state, was seen as a viable Democratic alternative to Clinton. Just last week, Warner traveled to Florida, a critical battleground state, to raise money and help other Democrats. He talked about how his ability to work with Republicans could appeal to Democratic primary voters.
"We have to really get it right and getting it right will require big enough change that it can't be a Democrat-only answer or a Republican-only answer." Warner said. "I think people ... even though they are hardcore Democratic activists, get that."
During his tenure as governor, Warner's approval rating was in the mid-70s in a state that hasn't supported a Democratic presidential nominee since 1964. His lieutenant governor, Timothy M. Kaine, rode that popularity last year to replace Warner, who left because of the state's one-term limit.
His centrist approach won over some Florida Democrats last week.
Rep. Allen Boyd, D-Fla., told a crowd at a Tallahassee fundraiser, "I am being unequivocal about this: I am supporting Mark Warner for president."
In Tampa, Democratic Party fundraiser and former state party executive director Ana Cruz said, "He's got a middle-of-the-road, common sense election message for Americans, which is what they want. We'll see after this election cycle that it's not about partisan politics, it's about who can govern the best."
Warner aide Jim Margolis said the 51-year-old Democrat understood that this was probably his best chance to run for president.
"He's not ruling out running for political office in the future. He will most certainly be involved in politics and the political debate," the aide said.
Warner could be considered for a vice presidential spot. Another possibility would be Sen. John Warner's seat in 2008. The five-term senator — no relation — is 79.
Mark Warner was elected governor in 2001, defeating Republican Attorney General Mark Earley. The former state Democratic Party chairman, who made a fortune in the infancy of the cellular telephone industry, had never held elected public office.
After a difficult start with a Republican-controlled General Assembly, Warner in 2004 brokered a compromise between Democrats, moderate senators and 17 House Republicans to pass a budget-balancing $1.4 billion tax increase. The tax increase was widely regarded as the signature initiative of his four-tear term.
Warner then returned to private business.