Asked in the Oval Office whether he was running for president, Biden told Wall Street Journal reporter Carol Lee, "Only if you're my running mate."
Standing near the doors as President Barack Obama described his meeting with United Nations Secretary General Ban Ki Moon, Biden wouldn't detail his plans further -- and slipped out of the room before Obama finished speaking.
The President himself only smiled and laughed when reporters asked him next about his vice president's future plans -- silent on the ever-swelling chatter about Biden's intentions.
Obama's muted response isn't a surprise -- a Biden candidacy would put him in an awkward spot between his second-in-command and his former top diplomat, Hillary Clinton -- and his aides have said he'll offer advice to Biden only if asked, and only in private.
A chance for political consultations could come later Tuesday, when the President and vice president sit down for their weekly lunch in Obama's private dining room.
Biden returned to Washington amid fresh speculation he's considering another bid for president, though his allies and aides say he's not likely to make a decision for at least another month or so.
He's still deeply in grief over the loss of his eldest son Beau. But his top supporters and aides are busy stoking speculation that he's taking another look at his 2016 prospects.
A potential rival for the Democratic nomination, former Maryland Gov. Martin O'Malley, said in South Carolina Tuesday he would "welcome" Biden into the primary race.
"People are looking for alternatives," O'Malley said. "They don't like being told who they're supposed to be voting for and they don't like the sinking sense in the air that somehow big money determines who our nominee is going to be."