US Vice President Joseph Robinette "Joe" Biden on Wednesday announced that he would not be running in the 2016 presidential elections, increasing former Secretary of State Hillary Clinton's chances of gaining the democratic nomination.

"As my family and I have worked through the grieving process, I've said all along that it may very well be that that process closes the window on mounting a realistic campaign for president, and I've concluded it has closed," Biden said at a press conference in the White House Rose Garden in Washington.

'Will not be silent'

Biden's son Beau died from brain cancer in May, casting doubts on the vice president's ability to launch a grueling campaign while he and his family mourned.

"I believe we're out of time, the time necessary to mount a winning campaign for the nomination," Biden said standing in between his wife and President Barack Obama.

However, the 72-year-old vice president added that he "will not be silent" in the upcoming US presidential election.

"While I am not going to be a candidate, I will speak out clearly and forcefully as to where we stand as a party and where we need to go as a nation," Biden said.

Clinton boost?

Social media was buzzing with news of Biden's announcement, with the right-wing conservative Tea Party saying they would focus their efforts on defeating Clinton.

Meanwhile, Democratic leader Nancy Pelosi supported Biden's decision by hailing his legacy as a "middle class warrior" and "all-American patriot."

While Biden had previously run for president in 1988 and 2008, he dropped out early both times. The vice president made a longstanding career as a senator from Delaware, spanning more than three decades in Congress.

Biden's exit from the race boosts Clinton's chances of claiming the democratic nomination as it spares her from running against a popular party member.

ls/msh (AP, AFP, Reuters, dpa)