Obama, D-Ill., has been good friends with Nunn since he was elected to the U.S. Senate in 2005 and they share a passion for seeking an end to nuclear arms proliferation, The Boston Globe reported Monday, adding that interviews with current and former government officials who know them say a pairing of the two is a real possibility.

Nunn, 69, served as a U.S. senator for Georgia for 24 years, amassing a record as a military expert who voted moderately on social issues but has always dismissed talk of vice presidential ambitions. Now, however, Nunn may be more open to run after endorsing Obama this year, the Globe said.

"(Nunn) sounds like he may be more open to it," Arnold Punaro, a retired Marine Corps general who served on his Senate staff, told the newspaper. "He has never before endorsed anybody. That was a surprise to me."

Unnamed sources said Nunn appeared more prepared to accept a vice presidential offer this time, which could help Obama's perceived lack of depth on national security.