Picked by Barack Obama, whom he challenged early on in the 2008 presidential primary, for the No. 2 spot on the Democratic presidential ticket, Biden, who represented Delaware in the U.S. Senate since first being elected 35 years ago at age 30, is known for a tenacity he says was instilled by his parents.
Recalling the tough times growing up in middle-class Scranton, Pa., and Wilmington, Del., when his father's financial fortunes turned sour, Biden said during his vice presidential acceptance speech in Denver last summer: "My dad told me, 'Champ, you get knocked down, get up.'"
His mother, he said, told him failure is inevitable in life "but giving up is unforgivable" and when bullies assailed him, she told him to go out and "bloody their nose so you can walk down the street the next day, and that's what I did."
He took that advice to heart. As a youth he overcame a serious stuttering problem to become a masterful debater. In college, he went from uninspired student to law school graduate. He became the second-youngest person ever directly elected to the Senate.
When tragedy struck and his first wife, Neilia, and infant daughter were killed in a car crash, he threw himself into being a single father to sons Beau and Hunter, who survived the accident, riding the train 110 miles each day to work at the nation's Capitol. He and his second wife, Jill Tracy Jacobs, have a daughter, Ashley.
When it came to his Senate career, Biden again drew from his mother's advice, following the philosophy that "everyone is your equal and everyone is equal to you."
A lunch-bucket Democrat with expertise in budget, judiciary, foreign relations and intelligence issues, Biden rose to ranking Democrat on the Judiciary Committee and led the Foreign Relations Committee. It is his depth of experience, particularly in foreign affairs where Obama was perceived as most vulnerable, that contributed to making him the young Illinois senator's pick as a running mate.
Among his duties, Biden sought to provide advice on critical decisions Obama would make, and was closely involved in all Cabinet appointments made during the transition.
Biden was the head of the White House Task Force on Working Families, an initiative aimed at improving the economic well being of the middle class.
Biden visited Iraq about once every two months, becoming the administration's point man in delivering messages to Iraqi leadership about expectations for the country's progress.
Domestically, Biden oversaw infrastructure spending from the Obama stimulus package meant to help jump start the economy, and spoke with leaders at all levels of government to ensure the monies were properly spent.
Biden has the reputation of being a loose cannon who often speaks off-script with sometimes outrageous results. On March 23, 2010, Biden was caught off-mike telling Obama that signing the Affordable Care Act was a "big [expletive] deal" during a live broadcast. More recently he told supporters during a campaign stop a Republican win in this election would put "y' all back in chains."