WASHINGTON (BLOOMBERG) - Donald Trump's impeachment team intends to lean heavily on his use of the words "peacefully and patriotically" in a Jan 6 speech as part of his defence against the charge that the former president incited a mob of supporters to storm the US Capitol, according to people familiar with the effort.

The former president's defenders are also assembling more than a dozen videos with what they hope will be a stronger argument after the rambling presentation by attorney Bruce Castor during the first day of his impeachment trial, the people said, a performance that was widely panned.

House managers serving as prosecutors have focused on Trump's comments during the Jan 6 rally urging his supporters to "fight like hell" and urging them to go to the Capitol.

But Trump also urged the crowd to "peacefully and patriotically make your voices heard." Democrats argue that while Trump did use those words, he also used "fight" and "fighting" more than 20 times, and that his efforts to overturn the election before the rally also contributed to the riot.

Trump's team intends to show footage of Democrats using words like "fight" and calling for protests of Trump's actions during his presidency to argue that he is being held to a double standard for his fiery rhetoric, according to the people, who were granted anonymity to discuss trial strategy.

"This is not about impeaching Donald Trump, it's about preventing him from ever running again," Donald Trump Jr, the former president's eldest son, told Newsmax on Wednesday. "If they wanted to impeach every member of Congress who ever used the word 'fight like hell' in a stump speech there would be no one left in DC," he said.

Trump's defence will also argue that a judge can't serve as a juror at the same time because the Senate's presiding officer, Patrick Leahy, a Vermont Democrat, is overseeing the trial despite having previously called for Trump's conviction, according to the people familiar with the team's thinking.

The former president's team believes that House managers made a very strong case on Wednesday, but aides are telling Trump it doesn't matter because there won't be enough Republican senators voting to convict him, the people said. Only six Republican senators voted on Tuesday to continue the trial after arguments about whether the trial of a former president is constitutional.