Former US president Donald Trump has launched a personal attack on senior Republican Mitch McConnell, calling him a “dour, sullen and unsmiling political hack”.

The statement is the latest sign of deepening divisions within the party, after Mr McConnell said Mr Trump was the one who incited the deadly attack on the US Capitol last month.

Mr McConnell said that only after he joined other Republicans in voting against the former president’s conviction during a Senate impeachment trial that accused Mr Trump of provoking the mob into action.

In a statement released by Mr Trump’s political action committee, he said: “The Republican Party can never again be respected or strong with political ‘leaders’ like Sen. Mitch McConnell at its helm.”

Of the leader of the Republicans in the Senate, the statement added: “Mitch is a dour, sullen, and unsmiling political hack, and if Republican Senators are going to stay with him, they will not win again.”

A spokesperson for Mr McConnell did not immediately return requests for comment.

Mr McConnell said he voted to acquit Mr Trump because the Senate has no jurisdiction over an ex-president – even though he had rejected a push from Democrats to start the trial when Mr Trump was still in office.

“There’s no question, none, that President Trump is practically and morally responsible for provoking the events of the day,” Mr McConnell said on Saturday, after Mr Trump, the only president to be impeached twice, was acquitted on a 57-43 vote.

“The people who stormed this building believed they were acting on the wishes and instructions of their president.”

Mr McConnell had remained loyal to Mr Trump during nearly all of his four years in office, when the pair were the two most powerful members of the Republican Party.

But, after Mr Trump spent months making baseless claims that election fraud cost him the November election against Democrat Joe Biden, Mr McConnell said that overturning the vote because of objections from the losing side would see American democracy enter “a death spiral”.

In his statement, Mr Trump criticised Mr McConnell for failing to do more to back his unfounded claims of election fraud.

He also said Mr McConnell “begged” for his endorsement in the senator’s home state of Kentucky while running for re-election last year – and suggested he would work to defeat Mr McConnell and his Republican allies, saying he planned to “back primary rivals who espouse Making America Great”.

“This is a big moment for our country,” Mr Trump wrote, “and we cannot let it pass by using third rate ‘leaders’ to dictate our future.”