Since the accident, Biden has made a practice of commuting the 80 minutes from Washington to his home in Delaware almost every night by train. In 1977, Biden married Jill Tracy Jacobs, with whom he has one child -- a daughter, Ashley.
Biden first sought the Democratic nomination for president in 1987, but ran into trouble when it was revealed that remarks he made during a closing statement at an Iowa debate were lifted in large part from a speech by British Labor Party leader Neil Kinnock.
Campaign aides explained that Biden had previously referenced the Kinnock speech with appropriate citation -- but the damage was done, and Biden left the race.
In 1988, Biden suffered two brain aneurysms, both of which required surgery.
Returning to the Senate after the surgery, Biden held on to his slot as chairman of the powerful Senate Judiciary Committee, where he presided over the confirmation hearings of failed Supreme Court nominee Robert Bork, and now-Justice Clarence Thomas.
Biden currently chairs the Senate Foreign Relations Committee, and is vocal on the issue of Iraq, promoting a plan for a "soft partition" of the country into three largely autonomous regions, and working on Senate legislation to start a phased redeployment of troops.
Last year, Biden published a memoir, "Promises to Keep: On Life and Politics," in time for a second White House run.
Despite strong reviews for his debate performances, Biden failed to garner more than 1 percent of the vote in the Iowa caucuses, finishing fifth behind Obama, former Sen. John Edwards, D-N.C., Sen. Hillary Clinton, D-N.Y., and Gov. Bill Richardson, D-N.M.
Biden and his Senate colleague and fellow Democratic presidential contender Sen. Chris Dodd, D-Conn., withdrew from the primary race on Jan. 3, 2008.
Since leaving the presidential race, Biden has focused much of his attention on his seventh Senate run.
He has long been mentioned among political observers as a possible vice presidential candidate, or perhaps even a possible Secretary of State.
Now he will hit the national campaign trail once again, interviewing with the American people for a new job for only the third time in more than 30 years.
Biden brings with him a long resume and the gravitas of a senior statesman -- a potent mix Obama chose over a field of younger, but perhaps less-experienced contenders.
ABC's Sunlen Miller and Sara Just contributed to this report.