Leading vice presidential candidates

Democrat

Sam Nunn: The former senator, 69, a defense expert, has advised Obama on nuclear issues and could help carry his native Georgia and other states in the South. But he’s been retired from electoral politics for more than a decade, and many gay Democrats oppose him because he helped block President Clinton’s proposal in 1993 to allow gays to serve openly in the military. Dick Morris, a former advisor to President Clinton, has said that Nunn would be for Obama what Vice President Dick Cheney was for President Bush - an elder statesman. It’s a compliment that may not impress many Democrats.  (John Bazemore / Associated Press)

Democrat

Joseph R. Biden Jr.: The chairman of the Senate Foreign Relations Committee has worked closely with Obama on Iraq and other issues. He would help close the nominee’s “experience deficit” on national security, but he’s publicly criticized Obama’s willingness to meet with leaders of Iraq and North Korea. And he comes from Delaware, one of the smallest states in the nation.

For the record: A graphic in Monday’s Section A said Sen. Joseph R. Biden Jr. (D-Del.) has criticized Barack Obama, the presumptive Democratic presidential nominee, for offering to meet with the leaders of North Korea and Iraq. Obama’s offer was to meet with the leaders of North Korea and Iran.  (Karen Bleier / AFP / Getty Images)

Democrat

Evan Bayh: People around Obama have confirmed that he is under consideration. The Indiana senator, a moderate, was a prominent Hillary Rodham Clinton supporter in the primaries, so his choice would be another step toward party unity. “There’s a lot to recommend him,” said one Democratic strategist who spoke on condition of anonymity because the Obama campaign has banned any comments on the selection process. “He’s safe.” Bayh’s keynote speech at the 1996 Democratic National Convention was not a home run, but Obama may not need another spellbinding orator on the ticket.  (Jay Laprete / Associated Press)

Independent Democrat

Joe Lieberman: He’s a close friend and ally of John McCain’s, but he’s not a Republican and he supports abortion rights -- so his selection would not be much of an olive branch to Republican Party stalwarts who haven’t fallen in love with their nominee. “He’s fundamentally a liberal,” the conservative National Review said last week.  (Karin Cooper / Associated Press)

Republican

Mitt Romney: He came in second in the primaries, but many conservatives remain hesitant about a Mormon from Massachusetts who was once seen as relatively liberal on social issues. “A lot of social conservatives still have qualms about the religious issue; that hasn’t gone away,” said Scott Reed, who managed former Sen. Bob Dole’s 1996 presidential campaign.  (Jack Dempsey / Associated Press)

Republican

Charlie Crist: The Florida governor has been a powerful vote-getter in an important swing state, but some conservatives aren’t sure he’s really one of them. “The business community doesn’t like him,” said Grover Norquist, president of Americans for Tax Reform, an influential anti-tax group. “Besides, if you can’t win Florida on your own, you’re not going to win.”  (Phil Coale / Associated Press)

Republican

Tim Pawlenty: The Minnesota governor, an early McCain supporter, was criticized by conservatives when he imposed a “health impact fee” on cigarettes to help balance the state’s budget, but at least some have come around. “I think he’s quite good,” Norquist said. “He held tight on taxes when it was really tough.” Reed added: “McCain loves him.”  (Alex Wong / Getty Images)