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Being vice president just might be enough Joe Biden, or maybe not.

In an extensive interview with GQ magazine, Vice President Joe Biden said he could "die a happy man" despite never serving as president, a position for which he has campaigned twice, but quickly noted that that doesn't mean he's not thinking about a run in 2016.

"I can die a happy man never having been president of the United States of America," Biden told GQ. "But it doesn't mean I won't run.

"The judgment I'll make is, first of all, am I still as full of as much energy as I have now? Do I feel this?" he said. "Number two, do I think I'm the best person in the position to move the ball? And, you know, we'll see where the hell I am."

Former Secretary of State Hillary Clinton is largely considered the lead contender for the Democratic presidential nomination in 2016, but Biden and other lawmakers, including Maryland Gov. Martin O'Malley, New York Gov. Andrew Cuomo, are often mentioned as strong candidates should Clinton opt not to run.

Only 14 U.S. vice presidents have ascended to the chief executive job, and Biden, who ran for the presidency in 1988 and 2008, displays two of their portraits in his office.

"And by the way, if you come in the office, I have two portraits hanging: one of Jefferson, one of Adams. Both vice presidents who became presidents," Biden, 70, said. "I joke to myself, 'I wonder what their portraits looked like when they were vice presidents.'"

And a Republican who once made a bid for the White House doesn't think "President Biden" sounds "preposterous," according to GQ.

"He's unique from the day he was elected before he was 30 years old," Sen. John McCain, R-Ariz., told the magazine. "He's unique in that he's had some role in every major national-security crisis that his nation has faced in the last thirty-five years. I don't know anyone like him in the U.S. Senate.

"Look at the number of times he's been able to conclude agreements. I would say he's been the most impactful vice president that I've known, certainly in modern times.

"Suppose the economy comes on strong," McCain said. "He's bound to get credit. … Of course, the State of the Union speech would be the longest in history."