Donald Trump continues to peddle conspiracy theories to aides and senators behind closed doors, according to reports.

The US President has been condemned by critics over his repeated refusal to accept uncomfortable facts, including his denial that Hillary Clinton won the popular vote during the 2016 presidential election.

But the 71-year-old has begun to fixate on his most notorious untruth in recent months; that former president Barack Obama’s birth certificate is fake, reports The New York Times.

The “birther” conspiracy theory was first peddled during the 2008 presidential race and asserts Mr Obama was ineligible to be president because he was not born a citizen of the US.

It is widely considered a racist reaction to Mr Obama’s status as the first African-American to become president of the country.

Despite appearing to drop the claims after taking office, Mr Trump has reportedly used private conversations to question the authenticity of his predecessor’s birth certificate in recent months.

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Mr Trump has also allegedly begun to suggest the infamous Access Hollywood tape, in which he is recorded saying he can grab women “by the p****”, is fake.

Despite apologising for the comments in the run-up to the election last year, the President has told allies the voice was not actually his, according to The New York Times.

Sarah Huckabee Sanders, White House Press Secretary, failed to deny Mr Trump considered the recording a fake.

“He’s made his position on that clear at that time, as have the American people in his support of him,” she said at a daily news briefing.

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Shutdown the government for over a month in an effort to secure funding for his wall With Mexico declining to pay for the wall, the president has faced difficulty in raising the required $5bn at home. Due to his demand that the money for the wall be included in the budget, and Congress's refusal, the government partially shut down on 22 December 2018. It remained shut for over a month, the longest period in history Getty Donald Trump's least presidential moments so far... Joking about the Nazi occupation of France to President Macron In this tweet from 13 November 2018, the president mocks Emmanuel Macron's suggestion of a "true, European army" by invoking the conflict between France and Germany in the world wars Donald Trump's least presidential moments so far... 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The billionaire has also never accepted he lost the popular vote to Ms Clinton, resorting to the false claim that there were millions of people who voted illegally. He has made this claim repeatedly in recent months, the newspaper alleges.

Jeff Flake, a Republican Senator and critic of the President, said Mr Trump’s disregard for “shared facts” is “dangerous to democracy”.

“On so many of these, there’s empirical evidence that says no: You didn’t win the popular vote, there weren't more people at your inauguration than ever, that was your voice on that tape, you admitted it before,” he said.