Democratic presidential hopeful Joe Lieberman (search) said Friday that if elected president, he would tap Republican Sen. John McCain (search) as Defense secretary.

Doing little to dispel the criticism that he's a closet Republican, Lieberman told Don Imus's (search) syndicated radio program that he would want the Arizona senator, a colleague and a friend, for the Pentagon post.

"If I were president — I'm going to get him into trouble now — but, I'd ask John McCain to be my secretary of defense," Lieberman said. "I have total trust in him. He's strong, he's independent and he's a hero."

After initially insisting it was a joke, Lieberman's spokesman Jano Cabrera conceded his boss was somewhat serious.

But, he added, "Sen. Lieberman recognizes that he's not exactly in a position to be making any Cabinet-level appointments, but if he were elected president, he would be honored to have his friend John McCain serve as secretary of Defense or elsewhere in his administration."

McCain heard the exchange on his car radio and laughed.

"Sen. McCain appreciates his good friend's tongue-in-cheek offer, but he plans to continue to serve the people of Arizona in the U.S. Senate, working with President Bush in the White House," said spokesman Marshall Wittmann.