One of the first contenders for the 2008 presidential race has pulled out.
Mark Warner said the race had come at the wrong time for him
Mark Warner, the Democratic former Governor of Virginia, said he wanted to have a "real life" rather than face two years of campaigning.
"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.
Warner was popular with centrist Democrats and rated highly among traditionally conservative Virginians.
He left office in January under Virginia's single-term limits for its governors, and has since been involved in fundraising for a Democratic campaigning group, Forward Together.
In office he emphasised building bridges with Republicans, but successfully put through a $1.4bn tax rise bill without losing popular support.
In a written statement about his decision to stand down, he said he had made up his mind after celebrating his father's 81st birthday and touring universities with his eldest daughter.
"I know these moments are never going to come again," he 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."