Still, there is a belief among those loyal to Biden that, notwithstanding the questions, the 2020 campaign could be uniquely set up to his advantage, as the electorate decides whether to continue the presidency of Donald Trump or end it after a single term. This is why Biden is currently leaning strongly toward running.
Four years ago, after the tragic death of his son Beau, Biden spent months weighing whether to run for his party's nomination. He did not really want to say no but, for family and other reasons, could not bring himself to say yes. He simply let the clock run out and acceded to the reality that it was too late to run.
This time, as one decision deadline after another has slipped away, some people have speculated that the same thing could be happening again. But this time is different. Four years ago, it would have been a surprise if had he challenged Democratic front-runner Hillary Clinton and a rising Sen. Bernie Sanders, I-Vt., for the party's nomination. This time, especially now that he has the blessing of his family to run and no less desire to be president, the surprise would be if he were to say no.
The timetable remains in question. As he explores his options and kicks the tires of a possible campaign operation (he is keenly focused on the digital side of things), Biden has been in no rush to declare his intentions. He resisted recommendations from some advisers to announce early in an effort to shape the race in his favor. He has chosen to wait, preferring to make himself less of a target and to see whether any of the other early entrants would significantly change the landscape.
The Democratic field now includes Sanders, Sens. Elizabeth Warren of Massachusetts, Kamala Harris of California, Cory Booker of New Jersey, Amy Klobuchar of Minnesota, Kirsten Gillibrand of New York, South Bend, Indiana, Mayor Pete Buttigieg, former San Antonio Mayor JuliÃ¡n Castro, and Washington Gov. Jay Inslee, among others.
Sanders, who raised a bucketful of money after announcing his candidacy, is hitting the trail this weekend with rallies in Brooklyn and Chicago. Former Texas congressman Beto O'Rourke, who captured imaginations of Democrats across the country during his race last year against Sen. Ted Cruz, R-Texas, could say soon if he will run. Others will decide soon, in part based on Biden's thinking. So far, nothing has happened to dissuade Biden that waiting has cost him.
Though the contest for the nomination is viewed as wide open, Biden's advisers believe the former vice president's stock is underestimated, or at least underappreciated. They believe Biden is not just a leader in the polls but a genuine front-runner - though if he runs it will not be as a classic front-runner, as he explores other, less conventional ways of conducting a campaign.
His advocates believe that his standing reflects something sturdier than mere near-universal name recognition. His stature that has been built up over years. Loyalists doubt that would change suddenly if he becomes a candidate.
There is another characteristic that those in his orbit believe he could bring to the race that few other candidates can claim: an appeal across the breadth of the party. He will have support from older Democrats certainly, but also the ability to compete for younger voters; support from men and from women; an attraction among white working-class voters as well as support from African Americans.
The early weeks of the 2020 contest have been dominated by issues, by a democratic socialist agenda first championed by Sanders in 2016 that has now been adopted at least rhetorically by many of the others. It has highlighted the power of the progressive wing of the party - to the enthusiasm of some and the concern of others.
Should he become a candidate, Biden is prepared to become part of that debate, building on the record of the Obama presidency. Trump and the Republicans already have signaled their determination to pin the "socialist" label on the Democrats. Biden would resist that by countering Sanders and some of the others on the left.
The Democratic race in part will be a battle of ideas. But Biden must count on electability as by far the paramount question on the minds of voters - in the primaries and the general election - because of Trump. In this formulation, the 2020 election becomes not just another presidential campaign but truly an existential moment for the country.
Biden will be betting that this isn't a normal election but rather one that will turn far more on questions about fundamental values than on the specifics of Medicare-for-all or the Green New Deal - or on votes or actions from three or four decades ago.
Biden has spoken publicly about his concern that, under Trump, the guardrails of democracy are being threatened, "sanded down, little by little, each small step designed to curb institutional safeguards and concentrate power in the hands of individual leaders," as he put it in a speech in Copenhagen last year. At the Munich Security Conference last month, he spoke of this moment as a "struggle for America's soul . . . [that] goes to who we are, what we stand for."
The case he is likely to make, if he runs, would focus on two aspects of electability. First, that a majority of voters have grown weary of an experiment with a president who came to office with no experience and whose tenure has produced nonstop turmoil. Biden could argue that he has the experience to be president on day one and the temperament to calm the nation. Second, and vitally important, that he can win where Democrats must win to defeat Trump, in Pennsylvania and Michigan and Wisconsin.
Biden's earlier campaigns ended badly. He dropped out of the 1988 campaign due to allegations that he plagiarized the speech of a British politician. In 2008, he never got traction against Obama and Clinton. This time he would begin after having spent eight years as vice president, a different launchpad than from a senatorial office.
There are many hurdles that could trip him up. His long record as a senator will be scrutinized and evaluated in the context of today's America, of greater multiculturalism and the #MeToo moment. His handling of Anita Hill's testimony during the heated confirmation battle over Justice Clarence Thomas will be an issue. Questions about his record on abortion will come into play, as will things he said about school busing when it was a divisive issue in the 1970s. His advocacy for the 1994 crime bill, which has been widely criticized of late by African-Americans and other, will be reexamined.
Biden is 76 years old and has been in public life for more than four decades. He is not a new face, at a time when his party might be looking for one. He is friendly toward some Republicans at a time when many in his party brook no such behavior. His points of reference sometimes are far in the past. If that translates into the kind of experience people want, it will be an asset. If it seems he is not current enough, it might become a liability.
And there is the question of whether he would take Trump's bait; demean and diminish himself by going into the gutter with the president. Does he have the discipline to run the race of his choosing? Or would he succumb to letting the president define the debate?
A year ago, criticizing Trump for disrespecting women, Biden bragged that if he and Trump were still in high school, "I'd take him behind the gym and beat the hell out of him." He quickly came to regret saying that and said so, but it was an indication of how easily he could slip up.
His advisers respect the strength of others in the field and know there are some Democrats, even those who like and respect Biden, who would prefer to thank him for his service and ask him to move on. Nothing is assumed, nothing taken for granted about the path forward. And, he must still give the green light. If he does, he might finally reach his long-sought goal of becoming president. But only if he is able to show that he is the right candidate for this moment in history.