Steve Bannon has issued an excoriating attack on Donald Trump’s family by dubbing his daughter Ivanka the “queen of leaks” and calling her husband Jared Kushner “immature”.

Mr Bannon, a former Trump campaign chief and White House aide, said Ivanka Trump was a “fount of bad advice” during the election and once called him an “f***ing liar”.

He claimed Mr Kushner “doesn’t know anything” about Mr Trump’s supporters and blamed him for meetings that left the campaign open to the charge of cosying up to the Russians.

The US president himself is not beyond Mr Bannon’s ire, according to a 7,000-word profile in Vanity Fair magazine of the man credited with helping win Mr Trump office.

Mr Bannon reportedly thinks Mr 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 the president is “like an 11-year-old child” and told an adviser he would consider running for the White House if Mr Trump does not seek re-election, according to the article.

Mr Bannon’s spokesman denied the latter, saying he is “100 per cent not running for president”.