The man who was credited with helping Donald Trump win the presidency of the United States is signing off 2017 with an attack on the President's family.

Steve Bannon has dubbed Trump's daughter Ivanka the "queen of leaks" and called her husband, Jared Kushner, "immature".

Bannon, the former Trump campaign chief and White House aide, said Ivanka Trump was a "fount of bad advice" during the election and that she once called him a "f***ing liar". He claimed Kushner "doesn't know anything" about Donald Trump's supporters and blamed him for meetings that left the campaign open to a charge of cosying up to the Russians.

The President himself is not beyond Bannon's ire, according to a 7000-word profile in Vanity Fair magazine. Bannon reportedly thinks Donald Trump has just a 30 per cent chance of making it to 2020, the end of his presidential term, given the chance of impeachment or being removed by his Cabinet under the 25th amendment. He also joked that the President is "like an 11-year-old child" and told an adviser he would consider running for the White House if Trump does not seek re-election, according to the article.

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Bannon's spokesman denied the latter, saying he is "100 per cent not running for President".

The comments mark another rift in the souring relationship between Bannon, who took over the running of the Trump campaign in the final months, and the President.

Bannon was credited with convincing Trump to adopt a more nationalistic agenda before the election and joined the White House after the victory. But he left in August after a bitter feud with other aides and returned to Breitbart News, the hard-right news website of which he is executive chairman.

Allowing Vanity Fair to join him on a speaking tour to Asia, Bannon does little to disguise his frustration with the President's daughter and her husband, both White House advisers at the age of just 36. "He doesn't know anything about the hobbits or the deplorables," Bannon said of Kushner, referring to a nickname for Trump's supporters. "The railhead of all bad decisions is the same railhead: Javanka."

He recalls a meeting when Ivanka Trump accused him of leaking in front of her father.

"She's the queen of leaks," Bannon replied. "You're a f***ing liar!" she reportedly hit back.

Abbe Lowell, Kushner's lawyer, said: "Steve Bannon may regret not being in the White House any more, but that is not an excuse for peddling false stories about Jared or anyone else."