House leaders on Monday appointed 13 lawmakers to serve on a newly formed bipartisan congressional task force to investigate the attempted assassination of former President Donald J. Trump, choosing mostly members with significant military or law enforcement experience.

Representative Mike Kelly, Republican of Pennsylvania who represents the district where the shooting took place while Mr. Trump spoke at a campaign rally, was named the panel’s chairman. The top Democrat on the task force will be Representative Jason Crow of Colorado, a former Army Ranger.

“We have the utmost confidence in this bipartisan group of steady, highly qualified, and capable members of Congress to move quickly to find the facts, ensure accountability, and help make certain such failures never happen again,” Speaker Mike Johnson and Representative Hakeem Jeffries, the minority leader, said in a joint statement.

In private conversations between the two leaders, Mr. Jeffries emphasized the need to appoint serious members to the panel, a proposition with which Mr. Johnson agreed, according to two people with knowledge of the discussions. Mr. Johnson also emphasized that the task force, which was formally created by a congressional act that unanimously passed the House last week, represent a cross section of views within the Republican Party.

Spots on the committee, which is seen as a high-profile assignment to close out the 118th Congress, were the subject of intense internal lobbying.

The appointment of one lawmaker, Representative Clay Higgins, Republican of Louisiana, sparked criticism because of his history of endorsing conspiracy theories, including about the Jan. 6, 2021, attack on the Capitol. Mr. Higgins, a former U.S. Army staff sergeant and former law enforcement officer, has claimed that the F.B.I. entrapped supporters of Mr. Trump into carrying out the riot, and that “ghost buses” took agents provocateurs to the Capitol to instigate the violence.