Operatives at the very highest levels of the Democratic Party threatened Joe Biden with forcibly removing him from office unless he stepped down, sources told The Post.

The well-orchestrated "palace coup" to stop the faltering president seeking re-election has been in place for weeks, but stubborn Biden fought against it every step of the way, a source close to the Biden family told The Post Monday.

The insider also made clear the anger, paranoia and frustration Biden displayed as the party elite circled around him and piled on the pressure.

AFTER BIDEN DROPS OUT OF RACE, DOCTORS REVEAL WHY THE DECISION MAY HAVE BEEN BEST FOR HIS HEALTH

Part of the "elaborate" strategy to remove Biden from the race – as he announced in a shock letter posted on X Sunday – was allowing him to debate Republican candidate Donald Trump last month on live TV in Atlanta.

During the car crash 90-minute debate, Biden appeared confused, slack-jawed and at one point he froze up, with his shocking performance turning the tide against him.

"That debate was a set-up to convince Democrats that he couldn’t run for president," the source said Monday.

As calls for him to bow out mounted, Biden insisted he would continue, but party bigwigs threatened to invoke the 25th Amendment to the US Constitution.

The amendment allows for the vice president and members of the cabinet to declare he is unfit to serve and force him to step down, the source added.

BIDEN MAKES BIZARRE CALL IN TO HARRIS HEADQUARTERS HOURS AFTER DROPPING OUT OF RACE

The White House and representatives from the Democratic National Committee did not immediately respond to The Post’s requests for comment.

Although Biden immediately endorsed Vice President Kamala Harris as the Democratic candidate for president, the source said Democratic delegates will be strongly encouraged to instead back Arizona senator and former astronaut Mark Kelly for president at the Democratic National Convention in Chicago in August.

Some holdouts have still yet to endorse Harris as Biden’s successor, despite less than a month until the convention and only four months until election day. Most notable among them is former President Barack Obama.

"We will be navigating uncharted waters in the days ahead," Obama said Sunday.

Following the debate, first son Hunter Biden suddenly became more involved in his father’s day-to-day business and insisted upon attending every official and unofficial meeting, the source said.

"Hunter felt he [Joe Biden] was being set up and he was very concerned about his father," the source said. "These people, these officials were not on Joe’s side."

Biden’s own staff did not have any forewarning about the bombshell decision to pull out of the race, which was known since at least Tuesday, the source said.

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Many were also shocked by the letter posted to Biden’s X account itself, as it was typed on his private letterhead rather than White House notepaper and signed electronically, the source said.

"Everyone was totally shocked," the source said. "It was pretty telling that Jill Biden tweeted a heart emoji and nothing else."

Democratic Party insiders have also known for at least two years how Biden was in decline, said the source.

"When I saw him a couple of years ago, it was frightening," said the source. "He was just repeating slogans and had no idea who I was."

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