The task force of seven Republicans and six Democrats will have subpoena power and “will move quickly to find the facts, ensure accountability, and make certain such failures never happen again,” they said.

Johnson and Jeffries did not name the people who will be on the task force, but Jeffries was not going to sign on unless Johnson signaled that he would appoint lawmakers serious about the task force’s mission, according to three people familiar with the process who spoke on the condition of anonymity because they were not authorized to discuss private conversations.

The shooting during the July 13 rally in Butler, Pa., killed one person, critically injured two others and wounded Trump, who was rushed offstage by Secret Service agents. The suspected gunman, Thomas Matthew Crooks, was killed by law enforcement officials at the scene.

A similar bipartisan effort to probe the attack on the United States Capitol on Jan. 6, 2021, by a mob of Trump supporters broke down after then-House Speaker Nancy Pelosi (D-Calif.) appointed two Republicans to join the committee that then-Minority Leader Kevin McCarthy (R-Calif.) opposed.

Marianna Sotomayor contributed to this report.