WASHINGTON >> Vice President Joe Biden looks like a man running for president, but he does not sound like it.

He flies around the country, making announcements, jogging in parades, giving speeches and enjoying the cheers. When he stops moving long enough to think, however, he makes abundantly clear that he does not have the fire for another campaign.

Other politicians express ambivalence before jumping into the presidential pool, but few if any voice the sort of doubts about their own capacity to undertake the ordeal as Biden has in recent days. In a call with Democrats, in a speech in Atlanta and on television Thursday night, he sounded like an unhappy warrior, still mourning his son, emotional, worn out, unsure of his future.

Rather than mounting a presidential campaign, Biden appears to be engaging in public therapy, working through grief in front of seemingly every camera in the nation. He saw Beau Biden, himself a budding politician who died in May at 46, as his legacy. With the younger Biden now gone, friends and advisers say the vice president is struggling with whether to run to honor Beau and create a new legacy.

"I’d be lying if I said that I knew I was there," he told Stephen Colbert on "The Late Show" on CBS on Thursday. "I’m being completely honest. Nobody has a right, in my view, to seek that office unless they’re willing to give it 110 percent of who they are. As I said, I’m optimistic, I’m positive about where we’re going, but I find myself — you understand it — just sometimes it just sort of overwhelms you and I can’t be — "

Then he stopped.

In a halting voice, Biden described a recent encounter with a soldier, who called out Beau Biden’s name and said he had served with him in Iraq.

"All of a sudden, I lost it," the vice president said.

He paused. "I shouldn’t be saying this."

He shook his head. "You can’t do that. You can’t do that."

Can’t do what, he did not say.

Many friends believe that he ultimately will not run, but they are trying to give him room to decide on his own. The lure is powerful for a man who has run for president twice before. Initially overlooked amid assumptions of a Hillary Rodham Clinton coronation, Biden now hears the siren song of Democrats calling out "Run, Joe, run."

Indeed, he has a greater groundswell of support now than in either of his campaigns in 1988 and 2008. Polls show him with a healthier base of support — 20 percent to Clinton’s 37 percent in the latest CNN/ORC survey — and advisers mapping out a path to the nomination imagine that the minute he announced, he would pick up 5 to 10 points, making it a legitimate contest, not a quixotic exercise.

But support also means he can opt not to run on his own terms — not because Clinton eclipsed him but because it was the right decision for his family. In some ways, friends and advisers say, this most unusual exploration is about finding the respect he has not always felt in a White House he served loyally.

"He wants respect — he’s always craved it," said one person who has worked with Biden and asked for anonymity to speak candidly. "He never wanted to be Uncle Joe who is irrelevant and comes to the parties and tells old stories."

Biden, who as a senator for 36 years had no boss, struggled at first to find his place working for Obama, who did not always appreciate his loquacious vice president’s gaffes. When Biden said in 2009 that the administration’s economic rescue efforts had a 30 percent chance of failure, Obama publicly laughed it off as another Uncle Joe moment.

At a subsequent lunch, Biden complained to Obama about being hung out to dry. Obama accepted the grievance and made a point afterward of not publicly making fun of his vice president. He had no time for those who suggested replacing Biden on the 2012 ticket.

But there were other moments of friction with the president’s staff. During the 2012 campaign, Biden’s advisers encouraged him to meet with party donors to maintain viability for a future presidential run. Obama’s campaign team, led by Jim Messina, took it badly, wondering if Biden was out for himself. Biden, in turn, bristled at anyone questioning his loyalty.

The tension blew up in May 2012 when Biden endorsed same-sex marriage in a TV interview before the president did. Obama’s aides, like David Plouffe, his senior adviser, were angry that he had forced the president’s hand, and some suspected Biden was positioning himself for a future campaign.

Messina and much of the Obama campaign apparatus enlisted with Clinton at the start of the second term without so much as a nod at Biden. The person who worked with Biden said the vice president and his wife, Jill, were "stung" when Obama gave a joint interview with Clinton as she left the State Department in what looked like a passing of the baton. Still, Biden did not ask anyone to wait for him.

As some advisers point out, every vice president feels anxious about his treatment by the West Wing. By all accounts, Obama and Biden have forged a genuinely close relationship, one on display at Beau Biden’s funeral.

"Joe, you are my brother," Obama said with evident feeling, hugging Biden and kissing him on the cheek.

"My sense is that he and the president are very close, they’re close friends, and he’s regarded by a lot of us as maybe not the closest person to the president in government but among them," said Sen. Thomas R. Carper, a Democrat from Biden’s home state, Delaware.

Jared Bernstein, Biden’s former economics adviser, said the White House overcame any tension.

"There were times where he leaned too far over his skis, and of course nobody liked that," he said. "But in terms of the weight of his experience and his intuitive sense of how a lot of our stuff was playing with the middle class, I think he got a lot of respect."

The White House lately has made a point of showing that respect. Josh Earnest, the White House press secretary, said the president entrusted Biden with important issues like the stimulus package, gun control, Iraq and Ukraine.

"Through it all, the vice president has been highly effective, which has earned him the respect and admiration of everyone who works in the West Wing, including, of course, the president," Earnest said.

Inside Biden’s circle, some aides, like Mike Donilon, are enthusiastic about a campaign, arguing that the country needs him. Biden’s chief of staff, Steve Ricchetti, is described as trying to help him navigate the process in neutral fashion but devising a strategy in case he runs. Some friends said Biden should.

"I’ve known the man for 40 years — this is his destiny," said Gary Hindes, who co-hosted a dinner at the 21 Club in New York featuring Biden this week. "He’s conducted his entire political life, I think, with the fact that he very well one day would be president."

He added: "Now, maybe he doesn’t get in. But if I were him, I would not want to look back and think I should have taken the shot."

Others, like Ted Kaufman, Biden’s longtime friend, adviser and successor in the Senate, are said to be more dubious while trying to support his decision-making process. Advisers describe Jill Biden as broken up about Beau’s death and unenthusiastic about a campaign. Biden himself is concerned about Beau’s widow and children.

Now he is in a position he never imagined. When he came to the White House in 2009, he told The New York Times, he considered the vice presidency "a worthy capstone in my career." He resolved to pave the way for Beau Biden to continue the legacy. Then his son got cancer.

Friends say his emotional struggle has grown more difficult since Beau Biden’s death, not easier. He mentions Beau all the time. At 72, he is struggling to make peace with this period of his life. And the country is watching him do it.

© 2015 The New York Times Company