Continued from page 1

But Mr. Obama still chose him as his point man on Iraq, and Mr. Biden traveled to the country countless times during his first two years in office to urge the Shiites, Sunnis and Kurds to move to political reconciliation. In debates about ongoing violence in Afghanistan, Mr. Biden vocally pushed to limit the number of troops and tried to focus the counterinsurgency mission more on al Qaeda than on the indigenous Taliban forces and other local Islamic militant groups.

Populist connection

Mr. Goldstein also argues that Mr. Biden has a more influential role than Mr. Gore, whose main assignments — climate change and “reinventing” government by ridding it of waste and abuse — were not necessarily at the heart of Mr. Clinton’s agenda.

Mr. Obama even called on Mr. Biden to use his experience as a former chairman of the Senate Judiciary Committee to help interview and vet Supreme Court candidates, a critical role other vice presidents haven’t played.

And Mr. Biden’s populist ability to connect with people made his presence a must at Mr. Obama’s White House “beer summit,” held in 2009 to smooth over the tensions of a meeting between black Harvard University professor Henry Louis Gates Jr. and the Cambridge, Mass. patrolman who arrested him in a confrontation outside his house, in a case that attracted national controversy.

“There’s a Trumanesque quality to Joe Biden,” said Barbara Perry, senior fellow and presidential scholar at the University of Virginia’s Miller Center. “He was viewed — and still is — as the man of the people, an average Joe, if you will. He has a very low net worth and a very compelling family story and a son in the Army. People can relate to that, and despite all the gaffes, people really like him.”