House Oversight Committee Chairman James Comer, R-Ky., said the assassination attempt against former President Donald Trump was "preventable," and said the committee is "concerned the Secret Service lacks the management to keep protectees safe."

"A former president and current candidate for president was shot in the head by a sniper within 500 feet of the podium," Comer said in his opening statement ahead of Secret Service Director Kim Cheadle’s testimony on Monday. "This is unacceptable. We are concerned the Secret Service lacks the proper management to keep protectees safe from bad actors. Americans demand answers, but they have not been getting them from the Secret Service. We are instead learning about the events surrounding the assassination attempt from whistleblowers and leaks. Americans demand accountability, but no one is yet to be fired for this historic failure."

Comer reiterated his call for Cheatle to resign.

Ranking committee member Jamie Raskin, D-Md., said it is Congress' responsibility to learn from the attempted assassination and to ask tough questions of the director as to how this could have happened.

"Some are calling it a miracle that former President Trump escaped this AR-15 attack, unlike so many thousands of our fellow citizens who have been killed or seriously committed in other AR-15 shootings," Raskin said. "Our job in Congress is not simply to marvel at miracles ... but to act as public policy legislators to do whatever we can to prevent future political violence, attempted assassinations and massacres."

Raskin said he and Comer are "determined to get the bottom" of the "stunning security failures."

He also called on Congress to ban assault weapons, noting that the gunman who shot Trump was 20 years old and used his father’s AR-15.

-ABC News’ Luke Barr

House Homeland Security Committee Chairman Mark Green, R-Tenn., is calling on Secret Service Director Kim Cheatle to resign.

"Cheatle argued the Secret Service could not position counter-snipers in the location of the shooter because of the angle of the roof. This was an absurd, unacceptable, and obviously unfounded excuse," he said in a statement. "Cheatle placed blame at the feet of local law enforcement for the failures of that day -- blatantly ignoring the fact that local officers indicated ahead of time they did not have the ability to secure the building that the shooter used to fire those fateful shots."

"Director Cheatle has rightfully admitted the near assassination of a former president was a failure. She even said the buck stops with her," Green continued. "For the good of this country, Director Cheatle must resign immediately."

Green will visit the shooting site in Butler, Pennsylvania, at 11:30 a.m. ET Monday with a bipartisan group of members on the House Homeland Security Committee.

House Republicans are expected to hold a vote later this week on creating a task force to investigate the attempted assassination of former President Donald Trump.

The resolution, entitled "Establishing the Task Force on the Attempted Assassination of Donald J. Trump," will be introduced by Pennsylvania Republican Rep. Mike Kelly – who represents Butler, Pennsylvania, where the Trump rally took place.

The task force will include six Republicans and five Democrats and issue its findings to the House no later than Dec. 13, 2024.

-ABC News' Lauren Peller

Over a week after the assassination attempt made on Donald Trump during his campaign event in Pennsylvania, the former president has confirmed he was not warned of the gunman's presence at the rally before shots rang out.

During an interview with "Fox News" Sunday, Trump said that "nobody" warned him not to take the stage, even after the U.S. Secret Service spotted the rally shooter.

"Nobody mentioned it; nobody said it was a problem," Trump said when asked if was warned.

"They could've said, 'Let’s wait for 15, 20 minutes, five minutes,'" Trump continued, adding he believes it was a "mistake."

Trump then questioned how the suspected shooter got on the roof and why he wasn’t reported despite people seeing him.

"How did somebody get on that roof? And why wasn't he reported?" Trump asked.

Trump’s running mate Sen. JD Vance, who joined the interview, echoed the sentiment, saying he believes "there are a lot of good field agents" but added someone higher up "really screwed up."

-ABC News' Soorin Kim