US Senate Republicans on Friday blocked creation of an independent commission to investigate the deadly riot by Donald Trump supporters at the Capitol in Washington, a move aimed at preventing a bipartisan probe ahead of 2022 midterm elections.

Ten Republicans would have needed to join all 50 Democrats to advance the measure, which had already cleared the House of Representatives with modest bipartisan support.

But only six Republicans voted in favor, a result that demonstrated the deep divide in Congress and the nation nearly five months after the violent January 6 assault -- and the influence that the former president continues to exert on the Republican Party.

Republican Senators Mitt Romney, Lisa Murkowski and Susan Collins were among those who bucked their leadership to vote in favor of moving to a final vote on the commission, which had the support of President Joe Biden and several former Republican lawmakers.

But powerful Senate Minority Leader Mitch McConnell argued that the panel would have been a purely partisan exercise that would add nothing to the Department of Justice and congressional investigations already underway.

Republicans argue that more than 400 people have been arrested for their part in the unrest, and that those court cases will help shed sufficient light on what happened.

In the House of Representatives, 35 of the chamber's 211 Republicans joined Democrats in support of the commission that was to be modeled after the panel convened in the wake of the 9/11 attacks of 2001 and which had strong bipartisan support.

Defenders argued the latest commission would have included five members chosen by the Democrats and five by the Republicans, with subpoena power resting with both sides.