Anthony Scaramucci, the former White House communications director who has become one of Donald Trump's most prominent critics, says there is one world leader he considers even "dumber" than his onetime boss: Nigel Farage, leader of the UK's Reform Party.

Scaramucci served as White House communications director during Trump's first term and was infamously fired just 10 days into the job. Since leaving the administration, he has emerged as a vocal critic of the president and his political movement, frequently attacking Trump in the media and endorsing his opponents.

In an interview published Wednesday by The i Paper, Scaramucci turned to the United Kingdom's far-right political movement, led by Farage and the Reform Party, which has been gaining momentum in recent electoral cycles. Farage, a veteran of British politics, previously led the UK Independence Party and was one of the most prominent faces of the campaign for Britain to leave the European Union before taking charge of Reform. Scaramucci said he recognizes a great deal that is "Trumpian" in Farage and his supporters, but argued that Farage lacks some of the essential tools and traits that helped Trump ascend to the presidency twice.

"He has Trump's guile and shamelessness, and he's got Trump's corruptibility," Scaramucci told the outlet. "But Trump is smart. He got to the American presidency twice. Farage doesn't have the political instincts Trump has, he doesn't have the bombast and the flair. In 2016, Trump had almost 100 per cent name recognition. Farage doesn't have that."

Elsewhere in the interview, Scaramucci was pressed on Trump's evident mental decline, having previously observed that the president appears to be "losing it, mentally." The ex-official said that, in his estimation, the widespread theory that Trump suffers from dementia is "B.S.," and suggested that the power afforded to him by the presidency has done more to change his character.

"Has he declined? We're all declining," he explained. "There's also the imperial nature of the presidency; the majesty, the power, the pomp, which has also changed him. Obama said it better than me: The presidency, if you're a good guy coming into the presidency, you can magnify your good guyness. If you're a bad guy coming into the presidency, guess what? It's going to magnify your bad guess."

Scaramucci also backed the idea that the presidency was a lifelong goal for Trump, and dismissed suggestions put forward by some that Trump was spurred into politics after being publicly ridiculed by Barack Obama in 2011 — an apparent reference to that year's White House Correspondents' Association dinner, where Obama delivered a series of jokes at Trump's expense while Trump sat in the audience. He added that Trump's relentless drive to force himself upon the world is the product of a "massive chip on his shoulder."

"I'm not a psychotherapist, but it's very important for him to force himself into the world, right? He's got to have his name plastered on every building. He's got to have different brands associated with his name," he said.