The surprise announcement by Biden at the Rose Garden of the White House with President Barack Obama standing by his side, paves the way for Clinton as the Democratic frontrunner.
"I will not be the candidate. I believe we're out of time, the time necessary to mount a winning campaign for the nomination. But while I will not be a candidate, I will not be silent," Biden said.
Biden was flanked by Obama on his right and wife Jill on his left. He said he believes that Obama had led the nation from crisis to recovery.
"We're now on the cusp of resurgence. I'm proud to have played a part in that. This party, our nation, will be making a tragic mistake if we walk away or attempt to undo the Obama legacy," he said.
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In a statement Democratic National Committee chair Debbie Wasserman Schultz appreciated that Biden gave thoughtful consideration to seeking the Democratic nomination for president in 2016. "While Vice President Biden will not be a candidate next year, his unwavering commitment to America's working families is a legacy each of our candidates will proudly carry forward," Schultz said.
Biden who lost his son Beau to cancer early this summer, said as the family and he have worked through the grieving process, he has maintained all along that it may very well be that that process, by the time they get through it, closes the window on mounting a realistic campaign for president.
Now that he is not running for the presidency, Biden said there is a lot of work to get done over the next 15 months.
"There is a lot that the president will have to get done, but let me be clear that we'll be building on a really solid foundation," he said.
"But it all starts with giving the middle-class a fighting chance. I know that you in the press love to call me 'Middle-Class Joe' and I know in Washington that's not really meant as a compliment, it means you're not that sophisticated, but it is about the middle class. It isn't just a matter of fairness or economic growth, it's a matter of social stability for this nation. We cannot sustain the current levels of inequality that exist in this country," he said.