Senate Republican leader Mitch McConnell said after the 2020 election that then-US president Donald Trump was “stupid as well as being ill-tempered”, a “despicable human being” and a “narcissist”, according to excerpts from a new book.

Mr McConnell made the remarks in private as part of a series of personal oral histories that he made available to Michael Tackett, deputy Washington bureau chief of The Associated Press, for his book The Price Of Power.

The new biography of Mr McConnell draws from almost three decades of his recorded diaries and from years of interviews with the normally reticent Republican, and will be released this month.

The animosity between Mr Trump and Mr McConnell is well known — Mr Trump once called Mr McConnell “a dour, sullen, and unsmiling political hack”.

Republican presidential nominee former president Donald Trump waves at a campaign event
The animosity between Donald Trump and Mitch McConnell is well known (Alex Brandon/AP)

But the Republican leader’s private comments are by far his most brutal assessment of the former president and could be seized on by Democrats ahead of the election.

Despite his strong words, Mr McConnell has endorsed Mr Trump’s 2024 run, saying earlier this year “it should come as no surprise” that he would support the Republican party’s nominee. He shook Mr Trump’s hand in June when he visited Republican senators on Capitol Hill.

Mr McConnell, 82, announced this year that he will step aside as Republican leader after the election but stay in the Senate through to the end of his term in 2026.

The comments about Mr Trump quoted in the book were made in the weeks before the January 6 2021 attack on the Capitol.

Mr Trump was then actively trying to overturn his defeat and Mr McConnell feared this would hurt Republicans in two Georgia runoffs, costing him his Senate majority. Democrats ultimately won both races.

Publicly, Mr McConnell had congratulated US President Joe Biden after the Electoral College certified the presidential vote and warned his fellow Republicans not to challenge the results. But he did not say much else.

Privately, he said in his oral history that “it’s not just the Democrats who are counting the days” until Mr Trump left office, and that Mr Trump’s behaviour “only underscores the good judgment of the American people. They’ve had just enough of the misrepresentations, the outright lies almost on a daily basis, and they fired him”.

“And for a narcissist like him,” Mr McConnell continued, “that’s been really hard to take, and so his behaviour since the election has been even worse, by far, than it was before, because he has no filter now at all.”

Ahead of the Georgia runoffs, Mr McConnell said Mr Trump was “stupid as well as being ill-tempered and can’t even figure out where his own best interests lie”.

Mr Trump was also holding up a coronavirus aid package at the time, despite bipartisan support.

“This despicable human being,” Mr McConnell said in his oral history, “is sitting on this package of relief that the American people desperately need.”

On January 6 2021, soon after he made these comments, Mr McConnell was holed up in a secure location with other congressional leaders, calling then-vice president Mike Pence and military officials for reinforcements as Trump supporters stormed the Capitol.

Once the Senate resumed debate over the certification of Mr Biden’s victory, Mr McConnell said in a speech on the floor that “this failed attempt to obstruct the Congress, this failed insurrection, only underscores how crucial the task before us is for our republic”.

The next month, Mr McConnell gave his harshest public criticism of Mr Trump on the Senate floor, saying he was “practically and morally responsible” for the January 6 attack.

Still, Mr McConnell voted to acquit Mr Trump after House Democrats impeached him for inciting the riot.