It took Joe Biden three campaigns and more than 30 years to win the presidency. It should come as no surprise that he’s resisting suggestions that he give it up now, barely a week after a disastrous debate performance sharpened doubts that he can win a second term.

He’s been in this position before. “Same thing happened in 2020,” he told ABC’s George Stephanopoulos on Friday.

A recurring pattern of setbacks, defiance and recovery has been the central narrative of Biden’s career. It’s a story he frequently tells — to himself, his family and his party.

“I’ve been knocked down before and counted out my whole life,” he told campaign workers Wednesday. “I learned long ago that when you get knocked down, you get back up.”

In earlier chapters, Biden’s gritty refusal to be counted out was a virtue. It fueled his 2020 comeback from early-primary failures, when doubters said he was waging a “zombie campaign,” to victory over then-President Trump.

But Biden’s signature defiance appears to be hardening into denial.

In his 22-minute interview with Stephanopoulos, he batted away questions about whether his moments of incoherence at the June 27 debate were signs of a deeper problem.

“I just had a bad night,” the president said — five times.

He dismissed the many polls that show him likely to lose to Trump, who has been convicted of 34 felonies in New York.

“All the pollsters I talk to tell me it’s a toss-up,” he insisted.

When Stephanopoulos noted that surveys show only 36% of voters have a favorable view of Biden, the president replied: “I don’t believe that’s my approval.”

And he said he wasn’t sure whether he has rewatched the debate to analyze his performance. “I don’t think I did,” he said.

It sounded as if the famous chip on Biden’s shoulder has grown so big that it’s interfering with his ability to understand why so many Democrats are worried.

“The president is rightfully proud of his record,” David Axelrod, who helped Barack Obama win two presidential elections, posted on social media. “But he is dangerously out of touch with the concerns people have about his capacities moving forward and his standing in this race.”

A handful of Democrats in Congress — five House members, according to a tally by the Washington Post — have publicly urged Biden to withdraw from the race. More than a dozen others have expressed concern over his ability to wage an effective campaign, without explicitly asking him to get out.

Behind them is a much larger number who refuse to be quoted but worry that Biden’s debate performance was more than just one “bad night,” and that the campaign will devolve into a white-knuckled watch over his faltering performance.

Former House Speaker Nancy Pelosi (D-San Francisco) voiced their bottom-line question bluntly in a recent television interview.

“Is this an episode, or is this a condition?” she asked, referring to Biden’s lapses during the debate. “When people ask that question, it’s completely legitimate.”

If the answer is a one-time episode, Biden stands a chance of convincing voters that he can be an effective president for four more years. If the answer is that he is suffering from a worsening condition, he needs to retire with grace and honor.

When Stephanopoulos relayed Pelosi’s question to the president, Biden batted it away. “It was a bad episode,” he said. “No indication of any serious condition.”

But he acknowledged that he has not undergone a full neurological or cognitive evaluation. “No one said I had to,” he said.

“I have a cognitive test every day,” he added, referring to the many meetings he attends as president.

Pelosi, who has not urged Biden to withdraw, said both presidential candidates should undergo more rigorous medical examinations.

“Both candidates owe whatever test you want to put them to, in terms of their mental acuity and their health — both of them,” she said.

Trump, who at 78 is three years younger than Biden and has never released detailed health records, is unlikely to embrace that idea. So Pelosi’s argument amounted to a plea to the 81-year-old Biden to undergo more tests for the sake of his party, whether Trump follows suit or not.

Democrats expect more shoes to drop next week.

The first week of polls after the debate showed Biden losing about two percentage points, giving Trump an average lead of 3.5% in the nationwide popular vote.

A drop of two points may not seem large, but Democratic strategists aren’t convinced that Biden has bottomed out. “It usually takes about two weeks for an event’s effects to percolate,” one said. So Democratic leaders will be anxiously awaiting results from more polls.

Because of the way electoral votes are apportioned, Biden would need a popular vote lead of at least 2.5% to call the race a toss-up. Trump’s current lead — which may not hold up, of course — puts the president far behind.

That’s one reason Democrats in Congress are increasingly edgy. The other is that a GOP landslide could doom their chances of holding their majority in the Senate and winning a majority in the House of Representatives.

That outcome would not only cost many Democrats their jobs, it would deprive them of the power to impede Trump’s plans to transform the federal government into an instrument of his whims.

Senate and House members will return to the Capitol on Monday after their July 4 recess. Once Democrats hold their caucus meetings, the trickle of those urging Biden to withdraw could turn into a flood.

The decision, many say, is up to Biden.

If the president bows out, party insiders are already discussing how they could organize a “mini-campaign” in the six weeks before the Democratic National Convention in Chicago begins Aug. 19.

But if the president stays in, party leaders will try to avoid a chaotic fight over his nomination on the convention floor. The last time a president’s renomination was challenged at a convention, when Sen. Edward M. Kennedy tried to oust then-President Carter in 1980, the outcome was a disaster for the party.

Biden says he’s sticking to his guns. “I am staying in the race!” he shouted at a rally in Wisconsin on Friday. “I will beat Donald Trump!”

When Stephanopoulos asked the president if he would withdraw if he was convinced that he cannot win, Biden replied: “If the Lord Almighty comes down and tells me that, I might.”

Our political parties usually take a year or more to choose a presidential candidate. It’s clearly going to take longer than 10 days to decide whether to unchoose one.