Since the rumor that Biden was taking a close look at the race was planted earlier this month, speculation has swirled, some of it even holding that he was on the brink of announcing a candidacy. But several people close to the vice president told me he has not made a decision. When he told a conference call of Democratic National Committee members, on Wednesday, that he wasn’t sure he had the “emotional fuel” for a run, most Biden confidants believed he wasn’t spinning to buy time, but being honest about the calculation he’s weighing.

“I don’t think he’s made up his mind, and those who say he has probably don’t know what they’re talking about,” one longtime Biden friend told me. This person was skeptical that Biden would end up running, but pointed out that poll numbers and conventional wisdom had never been the lodestar for a brash political prodigy who defeated an incumbent senator at age 29: “He’s not afraid of being a long shot.”

Biden’s calculation is threefold: emotional, political, and logistical. Amid the continuing toll of his son Beau’s untimely death, hurling himself into a campaign promises more trouble and hurt. But saying “no” would entail its own grieving process, as the lifelong pol closed the door for good on his political career, without having achieved his life’s goal.

Most Democrats believe it would be logistically difficult to form an organization to compete with Clinton at this point; she has the backing of most of the party establishment and donors. “It's likely too late for a meaningful operation,” particularly in Iowa, one unaligned strategist told me. But Biden backers point to Barack Obama as precedent for passion and personality beating supposed inevitability; more than one told me of a flood of calls and emails from potential Biden backers, many of them nominally committed to Clinton.

“A lot of former staffers have held back, hoping this would happen,” Ronni Council, a Nevada Democratic operative who directed Biden’s campaign in the early-voting state in 2008, told me. (Biden, who dropped out after a poor showing in the Iowa caucuses, never made it to the Nevada contest, and Council went on to work for Clinton.) On the other hand, Bob Osterhaus, a former state representative in Anamosa, Iowa, who endorsed Obama in 2008 but has not committed to a candidate for 2016, told me he could not detect any buzz for Biden on the ground there.

But if what Democrats need is a backup plan for a possible Clinton collapse—someone to turn to if things get worse, not better, for the frontrunner’s joyless juggernaut—is Biden really the man for the job? The ideal Clinton alternative might be a fresh-faced liberal from outside the Beltway; Biden is an aging establishmentarian. Despite a buzzed-about recent meeting with liberal darling Elizabeth Warren, the Massachusetts senator, Biden established a reputation during his decades in the Senate as a pragmatist, not a crusader. “His heart is very much in it,” another former Biden aide told me, “but the rest of it is very hard to figure out.”