Reuters reports that Butch Bowers and Deborah Barberi, two South Carolina lawyers, are no longer on Mr Trump's team, according to a source familiar with the situation who said their exit was a mutual decision.
A further source said that an additional three lawyers associated with the defence, Josh Howard of North Carolina, and Johnny Gasser and Greg Harris of South Carolina, are also off the team.
Mr Trump and Mr Bowers are said to have had differences of opinion over strategy ahead of the trial.
CNN reporteda person familiar with the departures as saying that the former president wanted the lawyers representing him to focus on his allegations of mass election fraud and that the election was stolen from him.
The legal team reportedly intended to focus on the legality of convicting a president after they have left office.
With the exit of the five lawyers, the defence team now appears to be in turmoil, and it remains unclear as to who might represent Mr Trump when the trial begins in the Senate on 9 February.
Members of the former president’s legal team from his first impeachment, Pat Cipollone and Patrick Philbin, are not expected to return. Other lawyers connected with Mr Trump have said that they will not participate.
Speaking on CNN, former prosecutor Elie Honig described the situation as “a mess” and that while there may have been a difference in opinion on strategy, it indicates there is something more at play, likely regarding the veracity of Mr Trump’s claims regarding election fraud.
“When you see something like this, what it tells you is there was a difference in terms of not necessarily just strategy, but if a defence lawyer believes he is be made to make an argument that is either a lie or dangerous or unethical, that's where you see resignations like this,” said Mr Honig.
“If the former president came to me, I would say something like ‘I am not doing that big lie thing’. I will argue constitutionality all day long. Maybe that your speech you gave didn't quite step over the line of the First Amendment. I don't agree with those arguments, but they are fair play," the former prosecutor said. "If he said, no you are going to rant and rave about this election was stolen, rigged, rigged, rigged — no, I would do what these lawyers did."
The conventional wisdom within the Republican Party appears to be to follow the argument that the impeachment process is unconstitutional as the president has already left office.
Forty-five Senate Republicans backed a failed effort last Tuesday to halt the impeachment trial on the basis that it was not valid under the Constitution.
The Senate will consider a single article of impeachment passed by the House of Representatives that charges Mr Trump with incitement of insurrection for his role in the lead up to the storming of the US Capitol on 6 January.
Given that 17 Republicans would need to join with Democrats to convict Mr Trump with a two-thirds majority of the Senate and only five voted against halting the trial it is widely assumed that he will not be convicted.
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