Donald Trump on Sunday named two lawyers who will join his impeachment defence team, one day after it was revealed the former president had parted ways with two other lawyers who had been set to defend him.

The two lawyers representing him will be David Schoen, an Alabama attorney, and Bruce Castor, a former prosecutor in Pennsylvania.

Mr Trump’s team revealed on Saturday that two South Carolina lawyers who were set to represent him at the trial starting next week were no longer participating.

Butch Bowers and Deborah Barbier, both South Carolina lawyers, have left the defence team in what one person described as a “mutual decision” that reflected a difference of opinion on the direction of the case.

Mr Trump, the first president in US history to be impeached twice, is set to stand trial in the Senate on a charge that he incited his supporters to storm Congress on January 6 as legislators met to certify Joe Biden’s electoral victory.

Republicans and Trump aides have made clear they intend to make a simple argument in the trial: that it is unconstitutional because Mr Trump is no longer in office.

Legal scholars say there is no bar to an impeachment trial despite Mr Trump having left the White House.

“The Democrats’ efforts to impeach a president who has already left office is totally unconstitutional and so bad for our country,” Trump adviser Jason Miller has said.