Joe Biden is a six-term senator from Delaware. First elected to the Senate in 1972 at age 29, Biden currently is the chairman of the Committee on Foreign Relations, which reviews matters related to foreign policy including treaties, national security initiatives and humanitarian assistance.
Biden unsuccessfully sought the Democratic Party's Presidential nomination in 1988. He again ran in 2008, but withdrew after the caucuses in Iowa on January 3, 2008.
Biden has over the last 30 years in the upper House also served as head of the Judiciary Committee, with its jurisdiction over anti-crime legislation, Supreme Court nominees and Constitutional issues.
Biden, a Catholic with blue-collar roots and a generally liberal voting record, could also help attract working class votes, considered a weak area for Obama.
As chairman of the upper house's Foreign Relations Committee, Biden is expected to play a key role in getting final Congressional approval for the India-US civil nuclear deal in the narrow time window available before the legislature adjourns for the year Sep 26.
Biden has himself vowed to push the India-US nuclear deal in the Congress "like the devil" if New Delhi gets its end done though admitted that its passage is going to be "very, very tight".
"I am going to push like the devil...," Biden said last month as he lauded Prime Minister Manmohan Singh's decision to go ahead with the deal despite the withdrawal of support by the Left parties.
In 2006 too, as a ranking member of the senate panel, he along with its then Republican chairman Dick Luger played a key part in getting Congressional approval for the Hyde Act, the US enabling law for the nuclear deal.
Back in August 2001, Biden offered bipartisan support as Republican President George Bush started moving on a broad front to strengthen relations with India, culminating in the nuclear deal, described as the symbolic centrepiece of their new strategic relationship.
In a letter to Bush then, he expressed support and indicated that the American economic and military sanctions imposed on India after a nuclear test in 1998 could be removed in time for a possible meeting between Bush and then prime minister Atal Bihari Vajpayee in New York in late September.
By lifting the sanctions on India, Biden said in an interview with the New York Times, the US would be "setting an example for Pakistan", a reference to New Delhi's non-proliferation record.
"I don't view this as playing India off China," he was quoted as saying. "There are all kinds of reasons to treat them as they are - a great nation."
But during his last senate run in July 2006, Biden also drew fire for a perceived slight of Indian Americans when he said that in Delaware, "you cannot go into a 7-11 or Dunkin' Donuts unless you have a slight Indian accent".