Washington — House Republicans are ramping up efforts to investigate the attempted assassination of former President Donald Trump and the apparent security lapses that allowed a gunman to get within striking distance of the GOP presidential nominee.

Lawmakers on both sides of the aisle have expressed alarm about how the gunman, 20-year-old Thomas Matthew Crooks, was able to open fire at the Trump rally in Pennsylvania, striking the former president in the ear, killing one attendee and seriously injuring two others. Republicans' ire has been directed at federal law enforcement leaders, with some sporadic calls for agency heads to step down.

Speaker Mike Johnson announced on Wednesday that he will create a special task force within the House to investigate the attack on Trump, saying in a social media post that "we need answers for these shocking security failures."

Johnson elaborated on Fox News, saying that he plans to set the task force up on Monday and explaining that it will work as a "precision strike," able to move quickly by avoiding some procedural hurdles that other investigatory avenues face in Congress. Johnson said it would be a bipartisan task force, made up of both Republicans and Democrats. 

The Louisiana Republican said he spoke with Department of Homeland Security Secretary Alejandro Mayorkas, who he said "did not have satisfactory answers" about the attack. Johnson said he's also spoken with law enforcement leaders, saying "the answers have not been forthcoming." And he made clear that he plans to call for Secret Service Director Kimberly Cheatle to resign. 

Meanwhile, the House Judiciary Committee announced on that it will hold a hearing next week on the FBI's investigation into the assassination attempt, with FBI Director Christopher Wray set to testify.

The developments come as a flurry of hearings are scheduled for next week to grill agency heads about the security failure. The House Oversight Committee asked Cheatle to appear on July 22, issuing a subpoena for her testimony on Wednesday when her attendance appeared in question. 

"Americans demand accountability and transparency about the Secret Service's failures that led to the attempted assassination of President Trump, but they aren't getting that from President Biden's Department of Homeland Security," Oversight committee chairman James Comer said in a statement accompanying the subpoena. "We have many questions for Director Cheatle about the Secret Service's historic failure and she must appear before the House Oversight Committee next week."

Chairman of the House Committee on Homeland Security Mark Green also invited Mayorkas, Wray, and Cheatle to testify before the committee on July 23. 

"It is imperative that we partner to understand what went wrong, and how Congress can work with the departments and agencies to ensure this never happens again," Green, a Tennessee Republican, said in a statement.

Later Wednesday, both the House and Senate will receive briefings on the assassination attempt from Justice Department, Secret Service and FBI officials, multiple sources familiar with the briefing told CBS News. Efforts to investigate the assassination attempt in the Senate are underway as well.

President Biden said earlier this week that he is directing an independent review of security and events at the rally to determine what went wrong, while the Department of Homeland Security's inspector general is opening an investigation into the rally's planning.

Kaia Hubbard

Kaia Hubbard is a politics reporter for CBS News Digital, based in Washington, D.C.

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