Pittsburgh (CNN) Make no mistake about it. Joe Biden was definitely running.

He's not yet launched a bid for president, but Biden sent a well-timed signal of exuberance and political vitality on Monday, leaving reporters and Secret Service agents in his wake as he jogged through adoring crowds on Labor Day in Pittsburgh.

The old Joe was back. And the crowd was cheering "Run, Joe, run!"

Beaming, and looking more joyful in public than at any time since the tragic death of his son Beau in May, the 72-year-old's energetic trek through streets lined with well wishers, who seemed delighted to see him, did nothing to quell speculation that he may jump into the Democratic presidential race.

And if his decision turns on his rapturous reception in the gritty Western Pennsylvania city, which is a bulwark of organized labor, there will be only one answer.

The question on everyone's lips was "Will Joe Run?"

"I am gonna run part of the parade," Biden told CNN's Brianna Keilar. "I feel like I am home right now," he said, deflecting questions about whether he would indeed jump into the race to challenge Hillary Clinton and Bernie Sanders for the Democratic nomination.

Photos: Photos: Vice President Joe Biden Photos: Photos: Vice President Joe Biden U.S. Vice President Joe Biden began his career in politics in 1972, winning election to the Senate at the age of 29 (he was 30 when he took office). The Delaware Democrat was reelected to the Senate six times, including 2008, before becoming the 47th vice president of the United States. Hide Caption 1 of 14 Photos: Photos: Vice President Joe Biden Biden is sworn in for his second term as vice president by Supreme Court Justice Sonia Sotomayor, with his wife, Jill, and son, Beau, by his side, on January 21, 2013, in Washington. Hide Caption 2 of 14 Photos: Photos: Vice President Joe Biden Biden presides over a ceremony in Baghdad to formally mark the end of the U.S. combat mission in Iraq on September 1, 2010. Hide Caption 3 of 14 Photos: Photos: Vice President Joe Biden Biden and President-elect Barack Obama wave to the crowd at their election night party at Grant Park in Chicago on November 4, 2008. Hide Caption 4 of 14 Photos: Photos: Vice President Joe Biden Biden speaks after being introduced as Obama's running mate while campaigning together after the Democratic National Convention in 2008. Hide Caption 5 of 14 Photos: Photos: Vice President Joe Biden From left, former Sen. John Edwards, Biden, Obama and Sen. Hillary Clinton at a debate of Democratic presidential candidates on April 26, 2007, in Orangeburg, South Carolina. Hide Caption 6 of 14 Photos: Photos: Vice President Joe Biden Biden releases his memoir, "Promises to Keep: On Life and Politics," in 2007. Hide Caption 7 of 14 Photos: Photos: Vice President Joe Biden As a ranking member of the Senate Foreign Relations Committee, Biden is interviewed on NBC's "Meet the Press," concerning the war in Iraq on August 14, 2005. Hide Caption 8 of 14 Photos: Photos: Vice President Joe Biden While chairman of the Senate Foreign Relations Committee, Biden meets Afghan students during a visit to Kabul in 2002. Hide Caption 9 of 14 Photos: Photos: Vice President Joe Biden Biden is welcomed back after undergoing surgery for an aneurysm in 1988. Hide Caption 10 of 14 Photos: Photos: Vice President Joe Biden Biden announces his candidacy for the Democratic presidential nomination in 1988. After three months he drops out, following reports of plagiarism and false claims about his academic record. Hide Caption 11 of 14 Photos: Photos: Vice President Joe Biden While on the Senate Judiciary Committee, Biden meets with Sen. Frank Church, center, and Egyptian President Anwar Sadat after the signing of the Egyptian-Israeli Peace Treaty in 1979. Hide Caption 12 of 14 Photos: Photos: Vice President Joe Biden President Jimmy Carter and Biden attend a reception for the Delaware Democratic Party in 1978. Biden was the first senator to endorse Carter's presidential candidacy two years earlier. Hide Caption 13 of 14 Photos: Photos: Vice President Joe Biden At a convention in 1972, Biden and his first wife, Neilia, and his two sons take a photo with Delaware Gov.-elect Sherman W. Tribbitt and his wife Jeanne. Neilia Biden died in a car accident a few months later, after his first election to the Senate, along with their infant daughter, Naomi. Hide Caption 14 of 14

When young local business owner Chris Fuget asked whether he would announce a 2016 run, the Vice President reached into the crowd to shake his hand and momentarily hesitated before answering: "I haven't made that decision yet."

Then, asked by a reporter what he made of the overwhelming reception on an unseasonably warm morning, Biden answered: "It's home."

Later, Biden gently teased a group of steelworkers, saying the press would portray his visit to Pittsburgh as a sign he was "competing with Bernie Sanders, who is doing a helluva job by the way."

When a man yelled out he should run for the White House, Biden replied : "You gotta talk to my wife about that." Biden's wife Jill, is reportedly wary about the prospect of another Biden presidential campaign.

Wearing a white polo shirt, and looking fit and trim, Biden had earlier repeatedly flitted from side to side of the downtown streets clogged with union workers, floats, and the thunderous brass of marching bands.

Seemingly liberated to be back in the state of his birth, Biden offered a likely preview of the blue-collar message he would hammer out if he does run in 2016 -- in a speech that attempted to co-opt some of the anger marking the riotous political season.

Small groups of Sanders supporters held up home made signs and watched Biden pass. There was no evidence of Clinton backers in the crowd. The former secretary of state was spending Labor Day in Iowa.

"I am hot. I am mad, I am angry," Biden roared as he bemoaned the way workers have been "clobbered" in recent years, and vowed to fight to ensure a share for the middle class of the profits the rich have enjoyed from rising productivity.

"Something is wrong, folks.... the level playing field doesn't exist."

"Why in God's name should a man or woman working in a steel mill making $50,000 pay a higher rate than someone that makes tens of millions of dollars a year on Wall Street? I mean, I am serious."

The warm reception for Biden's remarks showed the popularity of an economic message among blue collar Democrats based on the idea that the working and middle classes have been left behind an economy tilted toward the most well off. But it also hints at the complications Democrats will have making that case in 2016, when they will have been in control of the White House for nearly eight years.

Still grieving after the death of his son from brain cancer, the Vice President is torn over whether his family can bear the emotional toll of what would be his third presidential campaign.

"If I can reach that conclusion that we can do it in a fashion that would still make it viable, I would not hesitate to do it," Biden said last week at a synagogue in Atlanta.

Rich Trumka, the President of the AFL-CIO, who controls a valuable political endorsement for Democratic candidates introduced Biden as a friend, a brother and "a great champion of working men and working women."

Leo Gerard, of the United Steelworkers Union meanwhile made the implicit case that he was the true heir of the post-Great Recession era of job creation under President Barack Obama.

"Joe Biden has been in the room, he has been the voice of working people in that room."

Biden had been expected to make a decision by a self-proclaimed end-of-summer deadline, but associates now say an announcement by October 1 is considered more likely.

Clinton still holds a commanding lead in the polls. But as talk of a potential run grows, with Clinton unable to quell a controversy about the private email server she used as secretary of state, Biden is seeing a modest uptick in polling.

And among the crowd in Pittsburgh there was disappointment that he did not use the chance on Monday to formally declare a White House run.

"We thought today might have been the day," said Pittsburgh union worker Jack Gaffrey.

Keith Turner, also from Pittsburgh, argued there was definitely space for Biden even though Clinton and Sanders have been in the race for months.

"Bernie Sanders is too liberal and as far as Hillary is concerned, she has too much baggage," said Turner.

In the latest poll of New Hampshire primary voters by NBC/Marist released Sunday, Biden had support from 16 % of Democratic voters. That's half the total of Clinton, who herself trailed front runner Sanders by 9 points. In Iowa, Clinton saw her lead over Sanders decline by half and now leads him by 37% to 20% with Biden at 20%.

The question Biden must ask, alongside the emotional equation triggered by his son's death, is whether he has a true path to the nomination, with Sanders picking up strong support from the left of the party and with Clinton still popular.

"I think it is early enough for him to be sufficiently competitive, especially because of the longevity of his popularity in Western Pennsylvania," said Pittsburgh Councilman Dan Gilman.

Meanwhile, conservative businessman and Fox News boss Rupert Murdoch predicted Biden would both run and win the Democratic presidential nomination.

"Looks like Biden already running. Very likely he wins nomination and be hard to beat," he tweeted.