“I’m getting frustrated by the elites in the party,” President Joe Biden vented on MSNBC’s “Morning Joe.” “’Oh, they know so much more.’ Any of these guys that don’t think I should run, run against me.” When host Joe Scarborough mentioned that some donors want him to withdraw, the president snarled, “I don’t care what the millionaires think. … I am running.”

But many party loyalists are also frustrated — with the president. “Among Democrats,” reports Punchbowl News, “there’s an overwhelming sense of dread about November, combined with anger at Biden and those around him.” Most dissidents won’t go public, but one who has is Rep. Mike Quigley of Illinois.

“What we need right now — and what I think takes a spine — is to step aside and recognize the president of the United States doesn’t have the vigor necessary to overcome the deficit here and it’s going to affect us all,” he told CNN.

Biden won in 2020 because he was able to unify and energize all of his party’s factions, mainly because they were so terrified of a second Trump term. But after his dismal debate performance, that unity is cracking.

“Biden is seeing a different world than other Democrats,” blares a headline in the Washington Post. “Where they see polls predicting political calamity, he sees a dead heat,” they continue. “Where they see a rapidly aging man who should sit for cognitive tests, he sees no problem that can’t be fixed with a display of energy and force. Where they see a 90-minute debate that showcased the state of his mental acuity, he sees it simply as a ‘bad night’ as he fended off a jet-lag-induced cold.”

“In the eyes of a president who often relishes the mentality of an underdog,” concludes the Post, “he has taken a posture of Joe Biden Against the World (or at least some in his party).”

It is very difficult to run as an outsider when you’re the incumbent. Bashing “millionaires” rings false when you’re pleading for their donations. But in a sense, this “underdog” self-image is vintage Biden. He first ran for president 36 years ago, and has faced repeated rejections by the same “elites” he’s still steaming about.

In 1988, he withdrew before the primaries after accusations of plagiarism. In 2008, he finished fifth in the Iowa caucuses and quit that night. In 2016, he declined to run after Barack Obama backed Hillary Clinton instead of him. In 2020, he finished fourth in Iowa and fifth in New Hampshire before he was rescued by the Black vote in South Carolina — and a weak field of rivals.

The core narrative he tells voters — and himself — is that he always bounces back, he always overcomes adversity, whether its political pitfalls or personal pain. Biden’s biographer Evan Osnos calls this “a form of self-mythology about resilience” and writes in the New Yorker: “He once wrote about his father’s frequent admonition to ‘Get up!’ According to Biden, ‘That was his phrase, and it has echoed through my life.’ Over the decades, through tragedies and professional embarrassments, Biden repeated it so often that he elevated a flinty bromide into an affirming and reflexive life strategy.”

For Biden’s critics, this “self-mythology” is so self-centered that he’s ignoring political reality. They fear the president will drag down the rest of the ticket, ruining their careers and freeing Trump to pursue his deeply dangerous impulses.

Indeed, since the debate, the dismay in Democratic ranks continues to fester. Some feel deceived by the White House and are asking hard questions: Didn’t you know about his decline? Did you deliberately hide it from us — and the voters? Given the risks, how could you allow him to debate Trump? Is he really up to the job?

After watching Biden’s interview, New York Times columnist Bret Stephens summarized this rising tide of resentment: “It was … enraging to watch Biden insist he has the stamina for another four years as president, which he clearly doesn’t, and that he’s the Democratic Party’s best bet to beat Donald Trump, which he surely isn’t, and that he doesn’t need to take a cognitive test, which he absolutely must. The words for this are denial, arrogance and narcissism.”

If the critics are enraged, the president is entrenched. He’s surviving as the candidate, for now, but seems headed for defeat in November.

Much can still happen: Another disaster could force Biden out. Or he could somehow manage to win, especially if Trump self-destructs. But Democratic unity has been badly fractured, and the wounds will heal slowly.