The former vice president spoke Sunday night at an annual dinner hosted by the New Hampshire Democratic Party in a state that the 74-year-old has come to know well through two unsuccessful presidential campaigns of his own and two more as a running mate.
Biden, who advisers say is currently nowhere near making a decision on 2020, addressed the question head on. "Guys, I'm not running!" he said with a smile, as the audience in the hotel ballroom booed in response.
But if Biden insisted that 2020 was not on his mind, it was clear that he has spent much of the past four months trying to determine why Donald Trump has become President.
The former vice president's autopsy of the 2016 presidential race was painfully stark: Democratic candidates had simply failed to convince the American people that they understood the hopelessness plaguing the country.
"Trump was pretty smart. He made it all personal," Biden said. It would not have taken much for Hillary Clinton to win on Election Day, but too may Democrats decided to stay home, he continued: "I'm absolutely positive they wanted to be with us. But we have to prove again we understand that hopelessness."
Accompanied at the dinner by his wife, Jill, and speaking for a full hour, Biden also wholly rejected the current President's worldview, especially on the issue of immigration.
He warned that the values like dignity and optimism that are at the core of the country were being eroded.
The rest of the world, "they respect us because they think we remain committed to 'all men and women are created equal,'" he said. "But of late, they're being run roughshod over."
But Biden also insisted that the current political climate was just a passing phase.
"Tolerance has long been our greatest attribute," he said. "We've had our ugly periods, we've had our moments of shame, but the arc of this nation has been towards justice."
Biden has hardly shied away from the public spotlight since leaving office over three months ago, after having spent eight years as Obama's deputy and 36 years as a US senator from Delaware prior to that. And he's done little in the last 100 days to persuade his supporters that he has completely shut the door to a 2020 presidential run.
"I think I could've won," Biden said last month. "Do I regret not being president? Yes."
In a visit to his old stomping grounds on Capitol Hill in December, Biden was happy to oblige inquiring reporters.
"Yeah, I am. I'm going to run in 2020," Biden said when CNN jokingly asked if he planned to run for office again. Pressed on what office he would run for, he responded: "For president. What the hell, man?"
Biden concluded in the lead-up to the 2016 election that he would not run for president for a third time. It was a decision shaped by a devastating personal loss: His son, former Delaware Attorney General Beau Biden -- whom Biden has referred to as "his soul" -- died in 2015 from brain cancer.
It was clear Sunday that the death of his son still weighed heavily on him.
Visibly emotional, Biden wiped his eyes as he thanked his supporters in New Hampshire for having been there for him over the last few years.
"So many of you were so good to our Beau. And the way in which you wrapped your arms around us, if I started naming names, I'd name half the room," Biden said. "I really mean it."
With Trump's approval rating at a historic low for a new president and the first months of his presidency mired in controversies, Democrats are determined to take back the White House in 2020. If there is a desire for a bench filled with younger up-and-comers, Biden's name somehow continues to make the rounds.
Biden's longtime friend and adviser Ted Kaufman said it would be a while before Biden feels the need to make any kind of decision about 2020.
"That's a long way off. It'll be a long time before he'll have to think about that. And a lot will depend on where he is, where the country is, where the party is," Kaufman, who was appointed to Biden's Senate seat after his resigned to become vice president, told CNN. "Who knows where this presidency's going to be after 100 days? It's pretty daunting to predict where we'll be 100 days from now, let alone a year from now."
In February, Biden and his wife, Jill, launched the Biden Foundation
, which focuses on a range of issues including cancer research. He is splitting his time between the nation's capital, Delaware and Pennsylvania, working with separate institutes bearing his name
at the University of Pennsylvania and the University of Delaware,
"He's really been frankly just as busy as he was when he was in the White House," Kaufman said. "He's a happy warrior."
One Biden adviser cautioned that his appearance in New Hampshire on Sunday was entirely about his promise to stay involved with the Democratic Party rather than his own political future.
"He said when he left office he was committed to continuing to party build, staying involved in the Democratic party, and this is that," the adviser said.
But some of Biden's most ardent political supporters are holding out hope.
Steve Schale, a veteran Democratic strategist based in Florida who was a part of the Draft Biden 2016 effort, believes to this day that Biden could have won if he had jumped into the 2016 race.
"I can make a really compelling argument for why I think after four years of Donald Trump, a guy like Joe Biden will be exactly what the country wants," Schale said. "If he wants to do it in a couple of years -- sign me up!"