US Republicans on Sunday braced for a battle over the future of their party after Donald Trump changed lawyers days before his impeachment trial in an apparent sign he is determined to maintain the 2020 election was fraudulent.

Trump's Senate trial is due to start on February 9, but he parted ways with his legal team after they reportedly refused to focus their defense on his baseless claims of election fraud, rather than on constitutional issues.

The trial of the former president for alleged "incitement of insurrection" over the storming on the Capitol by his supporters has exposed a rift between Trump loyalists who dominate the Republican Party, and its moderate wing.

"The Senate trial... is going to call all Republicans to take a position more clearly," Arkansas Governor Asa Hutchinson told ABC's "This Week."

"President Trump has helped build the party in the last four years, I hope he does not help to destroy the party in the coming four years.

"We've got to have a regard for those people that supported Donald Trump... But at the same time, we don't want to gloss over the terrible actions that happened at the Capitol."

Trump looks increasingly likely to avoid conviction due to party support in the Senate -- where all but five Republicans already backed an attempt to throw out the case on constitutional grounds.

But the trial is still sure to see battle lines drawn over who controls the party following Trump's first-term defeat.

On January 6, Trump gave a fiery speech outside the White House exhorting his supporters to march on the US Capitol to overturn the election results.

The protesters then violently stormed the Capitol buildings in scenes that shocked the world.

- Trump still in charge? -
"The president's comments that day were partly responsible for what happened, for the horrible violence," Republican Senator Rob Portman told CNN's "State of the Nation." "What he did was wrong and inexcusable.

"I am a juror. I'm going to keep an open mind as we go through this (trial). But I do think that this constitutionality issue has to be addressed. We would be convicting a private citizen, someone who's out of office. That sets up a precedent."

Adam Kinzinger, one of 10 Republicans in the House of Representatives to vote for impeachment earlier this month, said Sunday that Trump was "desperate to continue to look like he's leading the party."

"We need to quit being the party that even an iota defends an insurrection, a dead police officer and other dead Americans on the Capitol," Kinzinger told NBC's "Meet the Press."

While signaling opposition to Trump's trial, Republican senators are instead fueling efforts to censure him over his role in the Capitol assault.

But while a conviction would lead to a simple-majority vote on whether to bar Trump from holding future public office, a censure resolution carries no such trigger.

Republican divisions have been further exposed in recent days by the newly-elected lawmaker Marjorie Taylor Greene, who has promoted the unhinged conspiracy theories pushed by the QAnon far-right movement, and backed Trump's false claims of election fraud.

Party leaders are under mounting pressure to take action against the lawmaker, whose past online posts have indicated support for executing Democrats and claimed school shootings were staged to undermine backing for gun rights.

But Taylor Greene has remained defiant, tweeting Saturday that she had had a "GREAT call" with Trump as she casts herself as a new champion of the party's Trumpist wing.

Asked if she was fit to serve, Hutchinson equivocated, saying party members should not be punished "because they think something a little bit different."

But Portman took a tougher line saying "Republican leaders ought to stand up and say it is totally unacceptable."

Trump, who left the White House for Florida before Joe Biden's inauguration, has vowed to stay active in politics in some form.

House Minority Leader Kevin McCarthy last week flew to pay homage to the former president at his Mar-a-Lago club in Palm Beach, keen to keep Trump's huge vote base on board as the party seeks to challenge Democrats for congressional control.