WASHINGTON — As the nation reels from the attempted assassination against former President Donald J. Trump and the Secret Service comes under intense scrutiny, U.S. Homeland Security Secretary Alejandro Mayorkas on Monday said “we are in a heightened and very dynamic threat environment.”

The former president and official 2024 GOP presidential nominee survived a shooting on Saturday that killed one person and left two others injured at a campaign rally in Butler, Pennsylvania.

“Both President Biden and former President Trump are constantly the subject of threats,” Mayorkas said during a White House press briefing in which he defended the performance of the Secret Service. Members of Congress are organizing hearings to examine whether security lapses occurred.

“The United States Secret Service, we, including the FBI and our other partners across the federal government, take the threats very seriously and adjust security measures as warranted,” Mayorkas said. He added that “maintaining the safety and security of the president, the former president and their campaign events, is one of our most vital priorities.”

Mayorkas said that in light of the shooting, Biden ordered Secret Service protection for Robert F. Kennedy Jr., an independent presidential candidate.

The secretary also said that “both prior to and after the events of this past weekend, the Secret Service enhanced former President Trump’s protection based on the evolving nature of threats to the former president and his imminent shift from presumptive nominee to nominee.”

Trump is in Milwaukee, Wisconsin, for the Republican National Convention, where he was officially nominated as the GOP presidential candidate on Monday alongside his newly chosen running mate, Ohio Sen. J.D. Vance.

Mayorkas also echoed Biden’s pledge Sunday for an independent review, saying it will “examine the Secret Service’s and other law enforcement actions before, during and after the shooting, to identify the immediate and longer term corrective actions required to ensure that the no-fail mission of protecting national leaders is most effectively met.”

In the aftermath of the shooting, Pennsylvania Democratic Gov. Josh Shapiro identified the person killed as Corey Comperatore, who was a former fire chief. Shapiro said Comperatore “died a hero” and “dove on his family to protect them” the night of the shooting.

The FBI is continuing its criminal investigation into the incident and has identified the shooter as Thomas Matthew Crooks, 20, of Bethel Park, Pennsylvania. Crooks was killed at the scene.

Mayorkas expressed support for Secret Service Director Kimberly Cheatle.

“I have 100% confidence in the director of the United States Secret Service. I have 100% confidence in the United States Secret Service and what you saw on stage on Saturday, with respect to individuals putting their own lives at risk for the protection of another, is exactly what the American public should see every single day. It is what I indeed do,” he said.

Pressed on CNN whether it was a security failure, Mayorkas said, “When I say something like this cannot happen, we are speaking of a failure.”

Congressional investigations multiply 

Meanwhile, lawmakers on both sides of the aisle have called for investigations into the attempted assassination of Trump.

The Secret Service is set to brief members of the U.S. House Committee on Oversight and Accountability on Tuesday.

The committee will also hold a hearing at the beginning of next week, once Congress returns from its week-long recess, with Cheatle set to testify.

“We are grateful to the brave Secret Service agents who acted quickly to protect President Trump after shots were fired and the American patriots who sought to help victims, but questions remain about how a rooftop within proximity to President Trump was left unsecure,” Rep. James Comer, chairman of the committee, said in a statement Monday.

“Americans demand answers from Director Kimberly Cheatle about these security lapses and how we can prevent this from happening again,” said Comer, a Kentucky Republican.

In a statement on Monday, Cheatle said the Secret Service understands the “importance of the independent review announced by President Biden yesterday and will participate fully.”

“We will also work with the appropriate Congressional committees on any oversight action,” she said.

Cheatle also noted that the “Secret Service is working with all involved Federal, state, and local agencies to understand what happened, how it happened, and how we can prevent an incident like this from ever taking place again.”

House Homeland Security Committee Chairman Mark Green wrote a letter Sunday to Mayorkas requesting multiple documents, saying “the seriousness of this security failure and chilling moment in our nation’s history cannot be understated.”

“No assassination attempt has come so close to taking the life of a president or presidential candidate since President Reagan was shot in 1981,” said Green, a Republican from Tennessee.

Senators also plan probes

Efforts to conduct investigations into the attempted assassination are also ramping up in the Senate.

Michigan Sen. Gary Peters and Kentucky Sen. Rand Paul — the respective chairman and ranking member of the Senate Homeland Security and Governmental Affairs Committee — said Monday that the committee is launching a bipartisan investigation and plans to hold a hearing soon to look into the “security failures” leading to the attempted assassination of Trump.

The two sent a letter to Mayorkas and FBI Director Christopher Wray asking for a briefing for committee members and requesting information from the Department of Homeland Security, the Secret Service and the Federal Bureau of Investigation. They also asked that either Mayorkas, Wray or an “appropriate designee” appear at a committee hearing on the matter by Aug. 1.

“There is no place for political violence in our nation, and Saturday’s shocking attack should never have been allowed to happen,” Peters said in a statement on Monday.

“Our committee is focused on getting all of the facts about the security failures that allowed the attacker to carry out this heinous act of violence that threatened the life of former President Trump, killed at least one person in the crowd, and injured several others,” he said.

Additionally, Sen. Lindsey Graham, a South Carolina Republican and ranking member of the Senate Judiciary Committee, led fellow GOP members of the panel on Monday in urging Chairman Dick Durbin to “hold a hearing into the circumstances that led to this tragedy.”

Graham and nine fellow Republicans also asked the Illinois Democrat to invite Cheatle, Mayorkas and Wray to testify in front of the committee.