A Trump campaign official told The New York Times that a lack of metal detectors to screen Trump event attendees had been a constant source of stress for the team.
The official said that the Secret Service had even tried to deny a request from Trump's team to install metal detectors at his son Barron Trump's high school graduation in May, which the former president attended with his wife, Melania.
The official told The Times that the Secret Service had argued that the graduation was not a "political" event before eventually caving in.
The official also noted that at one Trump rally in New York City in May, the lack of metal detectors created a backlog of people trying to enter the event.
It comes as the service went back on a statement saying that it had not turned down requests from Trump's team for additional federal resources in the two years prior to the assassination attempt in Butler, Pennsylvania on Saturday.
Secret Service spokesperson Anthony Guglielmi previously said that "there's an untrue assertion that a member of the former president's team requested additional resources and that those were rebuffed."
But Guglielmi said on Saturday that the Service had indeed rejected some requests for additional security resources, but these denials were not specifically for the Butler event, The Times reported.
In a statement to The Times, Guglielmi said: "In some instances where specific Secret Service specialized units or resources were not provided, the agency made modifications to ensure the security of the protected."
"This may include utilizing state or local partners to provide specialized functions or otherwise identifying alternatives to reduce public exposure of a protectee," he added.
The Secret Service has faced intense scrutiny since the Butler assassination attempt, during which 20-year-old Thomas Matthew Crooks of Bethel Park, PA, was able to scale a warehouse roof armed with an AR-15-style rifle and open fire at Trump — despite law enforcement officers already having raised concerns about someone acting suspiciously in the area.
Crooks managed to position himself only around 450 feet away from where the former president was speaking.
One bullet struck Trump's right ear. One person was killed, and two were critically injured during the incident. Crooks was killed by a Secret Service sniper.
Tim McCarthy, a former Secret Service agent who defended former President Ronald Reagan from a gunman in 1981, told Chicago-based outlet WGN-TV that the assassination attempt was a clear "failure" for the security operation.
"It's a failure. Plain and simple," he said. "Any time a protectee is harmed, there's something that has to change."
House Speaker Mike Johnson has since said that Congress would be conducting an investigation into security at the rally "to determine where there were lapses in security and anything else that the American people need to know and deserve to know."
Kimberly Cheatle, the director of the Secret Service, is set to testify before Congress on Monday.
On Friday, Guglielmi posted a statement on X that said the agency was "committed to better understanding what happened before, during, and after the assassination attempt of former President Trump to ensure it never happens again."
Business Insider contacted the Department of Homeland Security for comment.