Former US president Donald Trump has named two new lawyers to lead his impeachment trial defence, just one day after parting ways with his previous legal team.

David Schoen and Bruce Castor will defend Mr Trump on a charge of inciting an insurrection that led to the January 6 Capitol riots.

Their appointment comes after it emerged at the weekend that Mr Trump’s two previous lead lawyers, Butch Bowers and Deborah Barbier, were no longer a part of his defence team, just a week before the trial is due to begin.

Mr Trump and his new lawyers have just a day to respond to the charges of incitement before a Tuesday deadline.

According to American media reports, David Schoen is a federal criminal defence and civil rights lawyer who works in New York and Alabama.

He represented Roger Stone, a former associate of Mr Trump who was sentenced to prison for lying to Congress during the Russia probe.

Mr Trump commuted Mr Stone’s prison sentence in July 2020, saying he had been “treated very unfairly”.

Mr Schoen also met sex offender Jeffrey Epstein in prison before his death, reportedly to discuss legal representation.

Mr Trump’s office said Mr Schoen had already been involved with preparing the former president’s impeachment defence.

Donald Trump pardoned Roger Stone, who is a former associate of the ex-president. Photo: Getty

Bruce Castor is a former Philadelphia-area district attorney who specialised in prosecuting homicide cases.

He controversially refused to prosecute comedian Bill Cosby in 2005 for alleged sexual assault and sued Cosby’s accuser for defamation.

Mr Castor claimed she destroyed his reputation and political career by publicly criticising his handling of the case.

Cosby, 83, is in prison after being found guilty in a 2018 trial of drugging and raping a woman in 2004.

In a statement from the “Office of Donald J Trump”, the former president said both lawyers “agree that this impeachment is unconstitutional”.

Monday’s developments came as Republicans continue to mull whether to remove Liz Cheney as one of their leaders in the House of Representatives leaders for backing Mr Trump’s impeachment.

On Sunday, House Republican Adam Kinzinger, who also voted to impeach, announced a new political action committee called the Country First PAC, which is intended to challenge Mr Trump’s ongoing grip on the party.

Mr Kinzinger said his party had “lost its moral authority in a lot of areas” and under Mr Trump had pedalled “darkness and division”.

Liz Cheney was the most senior Republican to desert Mr Trump, but now faces her own demotion.

Lawmakers on the Republican right flank also want to remove Ms Cheney, the daughter of former vice-president Dick Cheney, as the party’s No.3 in the House.

House Republicans are expected to address the issue when they meet as a group.

The Democratic-led House voted on January 13 to impeach Mr Trump, with 10 Republicans voting in favour, on a charge of inciting a insurrection for his incendiary speech to supporters before the deadly Capitol siege.

Speaking to CNN, Senator Rob Portman urged fellow Republicans in the House not to punish Ms Cheney.

“I think she is very smart and she plays a key role in our party, particularly on foreign affairs. So I would hope that they would not go down that road,” he said.

During the impeachment debate, Ms Cheney said of Mr Trump’s actions: “There has never been a greater betrayal by a president of the United States of his office and his oath to the constitution”.

Republican leaders also may have to decide whether to take any action regarding first-term Republican congresswoman Marjorie Taylor Greene, who expressed support for executing Democrats, including House Speaker Nancy Pelosi, before she was elected.

Ms Greene first gained national attention for her interest in the QAnon conspiracy theory that falsely claims high-profile Democrats are part of a child paedophile ring.

Mr Portman said Republican leaders “ought to stand up and say it is totally unacceptable what she has said”.

There are strong indications too few Republicans will join the Democrats to achieve the two-thirds majority needed to convict Mr Trump in the Senate.

Last week, 45 of 50 Republican senators supported a resolution declaring the trial unconstitutional because Mr Trump is now a private citizen, having left office.

-with AAP