Veteran Senator Joseph Biden, 65, brings a working class background and a wealth of foreign policy experience to his new role as president-elect Barack Obama's partner in the next US administration.
Biden's no-nonsense style and 36 years in the halls of Washington power make him an ideal deputy to the 47-year-old Obama, a first-term senator unknown on the national stage four years ago.
Those qualities also made the Pennsylvania native a perfect foil for his Republican counterpart - John McCain's running mate Sarah Palin.
"Obama made an excellent choice. He is very strong in domestic policy, but is not as experienced in foreign affairs. Biden brings that expertise to the ticket," Professor Paul Herrnson at the University of Maryland said.
And putting Palin, a first-term Alaska governor and novice in foreign affairs and national security issues, up against Biden was in Herrnson's opinion a bad idea.
An Irish Catholic, Biden grew up in Scranton, Pennsylvania, a former steel and mining town long-affected by industrial decline in the second half of the 20th century.
His down-to-earth style and appeal to traditional grass roots Democrats gave him an edge in connecting with working class voters who were initially wary of Obama and his unusual background.
"Biden is certainly an asset to Obama. He was a very wise choice both because of his extended foreign policy experience and because he is a tough campaigner," agreed Richard Langhorne, a professor at the Rutgers university in New Jersey.
"Biden has travelled very widely, has a strong sense of US external interests and is widely believed to be wise on the general topic of foreign affairs."
The young Biden moved to Delaware at age 10 when his father relocated in search of employment.
On the campaign trail the senator often reflected on his childhood with stories culled from the streets on Scranton, which at times he had to walk barefoot as his family was so poor.
Growing up he was also hampered by a debilitating stutter, which was so bad that he was cruelly nick-named "Dash".
Biden has a compelling life story to match that of Obama.
He was first elected to the US Senate at the age of 29 in 1972, and shortly afterwards his wife and infant daughter died in a car crash that also left his two young sons badly injured.
Biden took his oath of office at their hospital bedside and for the next decades commuted daily to Washington by train so he could be home each night with his boys.
As chairman of the Senate Foreign Relations committee, Biden has met many of the leading actors on the world stage, and is an outspoken critic of the current administration's foreign policy.
Unlike Obama though, Biden was initially in favour of the 2003 invasion of Iraq, but has been critical of the handling of the subsequent years in the conflict since Iraqi dictator Saddam Hussein was toppled.
His Republican detractors also point out that he was against the first Gulf War in 1991, and suggested in 2006 partitioning Iraq between its Shi'ite, Sunni and Kurdish areas.
But the senator, who is on the telephone lists of many world leaders, was among the first to call former Serbian president Slobodan Milosevic a war criminal, and to call for the closure of the Guantanamo Bay military prison.
"Senator Biden brings a pragmatic, non-ideological approach to world affairs. He understands the importance of American leadership, but also knows the limits to American power," said expert William Antholis from the Brookings Institution.
"Senator Biden is particularly strong in understanding how the United States and its major allies need to work together to address a range of global challenges.
"You can expect his input to be particularly keen on Iraq, Iran and Russia, where the US and its allies have not always seen eye-to-eye."
AFP