Biden, according to a number of advisers and Democrats who have spoken to him in recent months, wants to run, or at least be well positioned to run, if and when he decides to pull the trigger. Biden has expressed a clear sense of urgency, convinced the Democratic field will be defined quickly — and that it might very well come down to a private chat with Hillary Clinton about who should finish what Barack Obama started.

“He’s intoxicated by the idea, and it’s impossible not to be intoxicated by the idea,” said a Democrat close to the White House. And the intoxication is hardly new. Officials working on the Obama-Biden campaign last year were struck by how the vice president always seemed to have one eye on a run, including aggressively courting the president’s donors. Obama aides at times had to actively steer Biden to places where he was needed — like Pennsylvania — because he kept asking to be deployed to Iowa, New Hampshire and other early states.

“He wasn’t just doing fundraising the campaign assigned to him,” said a campaign adviser. “He was inviting people to the mansion to hang out and have dinner.” Biden was way more into the donors than Obama was. “He embraced it with a tirelessness and a gusto that even the president didn’t,” another campaign official said.