But as he reaches the end of a long process of contemplating a run for President -- a decision could be imminent -- the Vice President faces an uncomfortable question: Will the union movement be there for him at his moment of greatest political need?
Labor has long been the backbone of Biden's career and his associates have signaled that the issues the movement cares about would be central to a presidential campaign. Former Sen. Ted Kaufman, a top Biden aide, said in a recent email to former staffers that a potential White House bid would be anchored in a "burning conviction that we need to fundamentally change the balance of our economy."
Given that, it might seem strange the question of union support needs asking at all.
But Biden, whose late-launching campaign would already face stiff headwinds, is suffering from a case of poor political timing.
The Vice President's deliberations on whether to run for president are coinciding with an outburst of fury in the labor movement about the vast Trans-Pacific Partnership trade deal that the Obama administration, in which Biden is a key player, recently celebrated. Many of the nation's top labor unions and advocates argue that the so-called TPP, which is central to President Barack Obama's vaunted rebalancing of U.S. power toward Asia, is bad for U.S. workers and will cost American jobs.
"I think that the opposition to the TPP in the labor movement is so strong, that it would be difficult to favor the TPP and have that not diminish one's ability to get labor union support," said Professor Joseph McCartin, a specialist on the political history of the union movement at Georgetown University. "I think that of all the impacts of the TPP, it really complicates the decision of Joe Biden as to whether or not he could run."
McCartin added: "He would have to walk a fine line -- he is well-loved and admired in the Labor movement -- but people would still have a problem with his support of TPP."
Tough political spot
When TPP comes up for a vote on Capitol Hill, the administration will likely have to rely on Republicans to pass it amid strong Democratic opposition -- which would put Biden in a tough political spot as a candidate for president.
It's a reality that Hillary Clinton, the Democratic national front-runner, has already acknowledged by coming out against a deal that she supported as secretary of state and once said could be a "gold standard" of global free trade pacts.
Her move, and Biden's straitjacket as a member of the administration that supports the TPP, significantly threaten the running room that the Vice President could expect to have in the Democratic primary.
In fact, unless Biden engineers an almost unthinkable break with the administration over TPP, he would be the only major Democrat on the ballot who backs the deal and would have to explain to grassroots voters why their view that it would punish the American worker is wrong.
Joshua Goldstein, a spokesman for the AFL-CIO, the federation that groups 56 unions representing 12.5 million workers, said that Biden was a "good friend" and "champion" of the union movement, without saying whether his stance on TPP would affect a possible endorsement.
"While it is a significant piece of the consideration for the support of working people, it is only one piece of what the raising wages agenda is about," said Goldstein. "Will it play a role? Absolutely, but there are a lot of different things that working people look at when they decide what leader they will support for the president."
As he moves toward a final decision on a run, Biden has been reaching out to key progressive power brokers around the nation -- including some of his oldest political allies in the union movement.
CNN's Jim Acosta reported for instance on Saturday that Biden spoke last week with Harold A. Schaitberger, president of the International Association of Fire Fighters, and strongly indicated he was planning to launch a White House bid.
Earlier this month, the New York Times reported that Biden would likely get the union's support if he did indeed run. The union backed also backed away from endorsing Clinton, the Times reported.
The endorsement -- despite the IAFF's opposition to the TPP, would not come as a surprise. Biden has long had emotional links to the union, and often relates in speeches how he believes firefighters saved his own life, rushing him to hospital through a snowstorm when he suffered an aneurysm in 1988 and those of his two young sons in a car crash that killed his first wife and infant daughter in 1972.
Given that Biden would be embarking on his campaign many months and millions of dollars behind Clinton and the vociferously anti-TPP Bernie Sanders, union organizing and door knocking would be particularly important to his campaign.
But his close ties to the union movement may not be sufficient to corral organized labor behind his campaign.
CNN's John King reported on Sunday that the vice president would likely be disappointed if he expected mass union defections from Clinton or Sanders. King cited several sources as saying that though the former secretary of state had won the backing of a number of national labor leaders who believe she is the most electable Democrat, many local chapters were keener on Sanders and were pushing back at national leadership.
Still, union backing or not, Biden would depend on his affinity for the working and middle classes should he run for the White House.
His speeches pulsate with pride at his blue-collar roots, highlighting his upbringing in the gritty Pennsylvania city of Scranton and mythologizing the honest toil of working Americans.
At a recent White House summit dedicated to giving workers a voice in the economy, Biden pointedly mentioned that he had recently had lunch with Rich Trumka, president of the AFL-CIO.
He made no secret of his union bona fides, complaining that "labor has gotten the short end of the stick for so long."
He said unions were "the only guys keeping barbarians at the gate.... the weaker labor is, the weaker the American worker is."
Biden also welcomed the embrace of a union crowd at a Labor Day parade in Pittsburgh, where he marched wearing a United Steelworkers baseball cap. The event marked the first time Biden sent overt political messages since the death of his son, Beau, in May.
Cheers of "Run, Joe, Run" and the euphoric reception the Vice President enjoyed as he jogged through the city streets slapping palms and giving hugs may have been an intoxicating incentive as Biden's deliberations heated up.
But Biden did not mention the threat many Americans workers see from trade deals and low-wage economies in Asia during his speech, instead blaming the woes of the union movement on an economy skewed towards Wall Street and the rich against the middle classes.
Many major unions have yet to announce endorsements in the Democratic presidential race -- a factor that has led to some speculation that key labor leaders are waiting to see if Biden steps into the race.
Support for trade
And polling also suggests that a Democratic Party candidate who is pro-trade will not necessarily be disqualified by many party members. In a Pew Research poll earlier this year for instance, 71% of Democrats said that growing trade is good for the nation, and 59% of Democrats surveyed last year supported the TPP.
But while the IAAF endorsement shows that the vice president's backing for TPP would not preclude some labor unions and rank and file members from supporting him, the vehemence with which union leaders have greeted the trade pact imply that it would be politically unpalatable for them to back a pro-TPP candidate.
For instance, Leo Gerard, president of the United Steelworkers, ripped the TPP deal this month as a continuation of a "disastrous U.S. approach to trade."
"The TPP deal shouldn't even be submitted to Congress, and if it is, it should be quickly rejected," he said in a statement.
Another union leader, Tom Buffenbarger of the 600,000 member International Association of Machinists and Aerospace workers (IAM), condemned the TPP because he said it would facilitate the export of U.S. jobs to nations like Vietnam, Malaysia, and Mexico and called on lawmakers to reject the agreement.
The Machinists had previously endorsed Clinton in August and praised her decision to come out against the TPP earlier this month as a sign of her "strong support" for American workers. Clinton has also already won endorsements from the United Brotherhood of Carpenters and Joiners of America, the Roofers Union, the Bricklayers union, the United Association of Journeymen and Apprentices of the Plumbing and Pipefitting Industry and the National Education Association, which has three million members.
Another union, National Nurses United, has endorsed Sanders -- and specifically cited its opposition to the TPP, which it describes as a handout to big pharmaceutical firms that will drive up drugs prices.
So if he does run for president, Biden will be starting from just as far behind his top two rivals Clinton and Sanders in collecting union backing as he is in fundraising and early state organizing.