Former president Donald Trump's legal team and US House impeachment managers released their pretrial briefs on Tuesday, revealing vastly different strategies before the Senate trial.
Mr Trump's lawyers say the Senate cannot impeach a president who has left office and that the speech he gave before a deadly riot at the US Capitol, for which the House has charged him with "incitement of insurrection", is protected by free speech.
The Democratic-majority House of Representatives impeached Mr Trump on January 13, exactly a week after a mob of his supporters stormed the US Capitol.
The riot occurred after he made a speech outside the White House while members of Congress met to certify President Joe Biden's electoral win.
"President Trump's responsibility for the events of January 6 is unmistakable," the House impeachment team said in an 80-page brief.
"President Trump's effort to extend his grip on power by fomenting violence against Congress was a profound violation of the oath he swore.
"If provoking an insurrectionary riot against a joint session of Congress after losing an election is not an impeachable offence, it is hard to imagine what would be."
Five people died in the riot, including a US Capitol Police officer. Two officers who responded to the riot died by suicide in the weeks after.
Mr Trump has is having trouble securing legal backing for his defence. Several lawyers left his team this week, while Bruce Castor and David Schoen joined it.
His lawyers addressed the issue of his speech, saying that it is protected by the First Amendment.
"After the November election, the 45th president exercised his First Amendment right under the Constitution to express his belief that the election results were suspect, since with very few exceptions, under the convenient guise of Covid-19 pandemic 'safeguards', state election laws and procedures were changed by local politicians or judges without the necessary approvals from state legislatures," they said in their 18-page brief.
The House impeachment lawyers covered the free speech argument in their brief.
"The First Amendment protects private citizens from the government; it does not protect government officials from accountability for their own abuses in office," they said.
The pretrial briefs are the latest formal step towards the start of the historic Senate trial. Mr Trump is the first US president to be impeached twice.
The trial is scheduled to begin during the week of February 9, in a decision reached by majority leader Chuck Schumer, a senator from New York.
While the scales are tipped towards Democrats in the Senate, with Vice President Kamala Harris holding a tie-breaking vote, 67 senators are required to convict a president in a trial.
There is continuing argument over whether a former president can be convicted after leaving office, although the House is presenting a defence saying that Mr Trump was impeached while president.
Last week there was a vote on whether to dismiss the trial on constitutional grounds and 45 of 50 Republican senators voted to do so.
"Donald John Trump, 45th president of the United States, respectfully requests the honourable members of the Senate of the United States dismiss Article I: Incitement of Insurrection against him as moot and thus in violation of the constitution," the legal brief read.
It said "the Senate lacks jurisdiction to remove from office a man who does not hold office".
"In the alternative, the 45th president respectfully requests the Senate acquit him on the merits of the allegations raised in the article of impeachment."
Many constitutional experts say it is legal to hold an impeachment trial after a president has departed.
While the vote in the Senate last week did not confirm how any senators will vote in the trial, it shows that a conviction, with the support of 67 or more politicians, may be out of reach.
If Mr Trump is convicted, it opens a way for the Senate to vote on stopping him running for office again.
