Whitney Tilson, a longtime Wall Street investor and Democratic donor, has accused Joe Biden of “deceiving the American people” about his mental fitness for office — and is demanding that he step down immediately as the partys 2024 presidential candidate.

The 57-year-old money man — who made a bundle during the financial crisis, only to shutter his hedge fund Kase Capital in 2017 — told The Post that Biden should allow a younger rival to take on Trump and save the US from a four-year nightmare following his CNN debate debacle last week.

I feel like I have been deceived, Tilson said. Biden and the people around him have been deceiving the American people.

The dam has broken. We all know and we can all see that we were lied to.

I am deliberately calling it a Big Lie because this is as big a lie as Trumps Big Lie, he added, referring to the former presidents claims that the 2020 election was rigged.

Shortly after speaking with Post, Tilson tweeted a parody video that purports to show Adolf Hitler ranting about Bidens disastrous debate performance.

We are f*****d, he is incorrectly translated as saying.

The clip, a popular Internet meme, is in fact from the German language film Downfall that focuses on the Nazi leaders final days in Berlin.

Tilson said the Democrats should find a replacement and that he would back whoever came out on top.

I hope that Kamala (Harris) throws herself into the horse race, Biden cannot just anoint her, he told The Post by telephone from Italy. If she emerges as the first choice then I will support her.

The Wall Street veteran suggested two possible joint tickets that he believes could take on Trump.

He said his first choice was New Jersey Senator Cory Booker with ex-Rhode Island governor Gina Raimundo as a vice-presidential pick.

Booker could catch lightning in a bottle in the way Barack Obama did in the run-up to 2008, Tilson said.

He argued that Michigan Governor Gretchen Whitmer and Maryland Governor Wes Moore would also be a match for Trump this November.

His comments come as pressure continues to build on the 81-year-old to quit the race for the White House.

Biden repeatedly stumbled and mumbled his way through the 90-minute minute clash with his 2020 presidential nemesis.

His poor showing sparked concern from the Democratic partys major donors, who have blamed the presidents inner circle of advisors for encouraging him to stay on.

But criticism also came from left-wing media outlets such as MSNBC which have repeatedly ignored worries about Bidens cognitive faculties throughout his entire term.

The White House even lashed out at the Post after this outlet published a front page story that branded Biden the Meander in Chief after he wandered off at a recent G7 summit in Italy.

But it is not just megabucks Democrats who are worried about whether the former senator for Delaware can manage another four years in the biggest job in the world.

A recent poll carried out by USA Today and Suffolk University also found that Biden’s core supporters doubt whether he should stay in the 2024 presidential race.

The survey, conducted after the CNN debate, found that more than four in ten Democrats said the party’s top brass must demand that Biden stand down as the nominee.

On average, 54% of the voters polled were in favor of Biden dropping out.

But only 14% of Republicans said that the Republican Party should replace Trump as nominee, even after his recent conviction.

The real estate mogul was handed a boost by a Supreme Court ruling on Monday that found he enjoyed partial immunity in carrying out his official duties as president.

It could scupper the plethora of cases being brought against him that Democrats hoped would eventually sink his campaign.