Donald Trump lied to his Republican base and thought they were so stupid they would believe it, according to Jared Kushner.

Kushner, a property developer who is both Trump’s senior advisor and son-in-law, reportedly made the remarks after he was challenged about Trump’s prolonged interrogation over whether Barack Obama was born in the US.

During Obama’s 2008 presidential campaign and throughout his presidency, multiple theories falsely emerged claiming he was not a natural-born American citizen and it was therefore unconstitutional for him to become president. Trump was among those who pushed the “birther” conspiracy theory and consistently questioned former President Obama’s birthplace of Hawaii.

The former editor of the New York Observer claimed that Kushner, the former publisher of the paper, informed her that Trump did not believe the “birther” lies he was peddling.

“When I was the editor of the New York Observer, Kushner and I were going back and forth about how the paper should cover him,” Elizabeth Spiers wrote in a post on Twitter.

“I told Jared that I was particularly appalled by his father-in-law’s birtherism stance, which I viewed as cynical and racist.

“He rolled his eyes and said ‘He doesn’t really believe it, Elizabeth. He just knows Republicans are stupid and they’ll buy it’”.

My response to a right-wing blogger who called me a kook and a loser for stating that Donald Trump is a liar / water is wet: pic.twitter.com/pAp18w2x3W

— Elizabeth Spiers (@espiers) May 28, 2017

Spiers, who served as the editor of the publication from early 2011 to late 2012, made the alleged revelation in order to prove to a right-wing blogger that Trump was a “notorious liar”.

“Let’s be clear he was talking about you, Doug,” she says. “Trump did not con Democrats; he conned – and is still conning – his base. So you have every right to your gullibility and I won’t try to deprive you of it, but personally, I’d rather know what the hell is going on”.

Spiers also claimed that a friend of the then mogul-turned-politician once told her Trump would “lie to you about what time of day it is, just for the practice”.

But she is not the only person to argue that Trump is a liar. It has been asserted by a number of politicians and commentators, with Vermont Senator Bernie Sanders branding Trump a “pathological liar”.

“What do you do when you have a President-elect, soon to be President, who – and I say this not happily but I think most people who observe him would agree – is a pathological liar who changes his mind every single day?” said Sanders, who challenged Hillary Clinton for the Democratic presidential nomination.

As of April 2019, Trump has made over 10,000 lies, according to the Washington Post.