Former US president Donald Trump on Tuesday urged Republicans to not support the creation of a 9/11-style commission for investigating the Capitol attack, a day before the House of Representatives is set to vote on the matter.

The Democratic-backed proposal was approved in the House of Representatives Rules Committee earlier, setting up a planned vote in the full House on Wednesday. The committee is supposed to investigate Mr Trump’s role in spurring the riots.

“Republicans in the House and Senate should not approve the Democrat trap of the January 6 Commission,” the statement from Mr Trump said. “It is just more partisan unfairness and unless the murders, riots, and fire bombings in Portland, Minneapolis, Seattle, Chicago, and New York are also going to be studied, this discussion should be ended immediately,” he said.

“Republicans must get much tougher and much smarter, and stop being used by the Radical Left. Hopefully, Mitch McConnell and Kevin McCarthy are listening!” it added.

House minority leader Kevin McCarthy has already announced opposition to the proposal, saying it does not put enough focus on other violent riots that happened in the country as well as incidents such as the 2017 shooting of GOP lawmakers at a congressional baseball game.  However, these incidents are unrelated to the January attack.

“Given the political misdirections that have marred this process, given the now duplicative and potentially counterproductive nature of this effort, and given the Speaker’s shortsighted scope that does not examine interrelated forms of political violence in America, I cannot support this legislation,” Mr McCarthy said in a written statement Tuesday.

If the proposal is approved in the House, it will move to an evenly split Senate between Republicans and Democrats. If the legislation passes, the 10-member committee would have subpoena authority and would study the events leading up to Capitol riots.

On 6 January, hundreds of Trump supporters stormed the Capitol, interrupting the formal congressional certification of President Joe Biden’s election victory, and fighting with the police. The rioting killed five people, including a police officer.