PITTSBURGH – Republican Tennessee Sen. Marsha Blackburn on Tuesday asked the Secret Service's new acting director why the "public has lost trust" in the agency's "mission to protect" following a July 13 assassination attempt against former President Trump at his rally in Butler, Pennsylvania.

"This agency needs to change, and if not now, when? The next assassination in 30 days?" Blackburn read from an email, reportedly sent by a Secret Service counter sniper, during a Senate hearing involving testimony from Acting U.S. Secret Service (USSS) Director Ronald Rowe and FBI Deputy Director Paul Abbate. 

Blackburn also read the last portion of the email, obtained by Real Clear Politics reporter Susan Crabtree and reportedly sent within the agency by the counter sniper, stating that the "motto" of the USSS is "CYA," an acronym for "cover your a--."

The Tennessee senator continued: "The public has lost trust in the ability to execute the mission to protect, and I want to know how you feel about the fact that employees in your agency are worried about "covering their behind and not worried about protecting a former president."

TRUMP SHOOTING: TIMELINE OF ASSASSINATION ATTEMPT

Sen. Blackburn grilled the Secret Service on Tuesday about the public's trust in the agency following the July 13 assassination attempt against former President Trump. (Bill Clark/CQ-Roll Call, Inc via Getty Images)

The counter sniper who wrote the email apparently sent it to the entire Uniform Division as more information about the assassination attempt became public, according to Crabtree.

For example, Republican Iowa Sen. Chuck Grassley on Monday released text messages from Butler County, Pennsylvania, showing that snipers spotted shooter Thomas Crooks approximately 90 minutes prior to the moment he fired multiple rounds toward the former president, ultimately killing 50-year-old Corey Comperatore and injuring 74-year-old James Copenhaver and 57-year-old David Dutch.

TRUMP ASSASSINATION ATTEMPT: SENATE TO GRILL SECRET SERVICE, FBI OFFICIALS

Acting U.S. Secret Service Director Ronald Rowe Jr. testifies before a joint hearing of the Senate Judiciary and Homeland Security and Government Affairs committees in the Dirksen Senate Office Building on Capitol Hill on July 30, 2024 in Washington, DC (Chip Somodevilla/Getty Images)

Rowe, who took on the position of director after Kimberly Cheatle resigned last week, told Blackburn he is "hurt" by the email.

"I'm hurt because my people are hurting right now," Rowe told Blackburn. "We need them."

TRUMP ASSASSINATION ATTEMPT: TEXTS REVEAL OFFICERS WERE AWARE OF THOMAS CROOKS 90 MINUTES BEFORE SHOOTING

Sen. Marsha Blackburn, R-Tenn., read from an email that a Secret Service counter sniper reportedly sent to the entire Uniform Division on Monday evening expressing his disappointment in the agency's handling of the July 13 Trump rally and public distrust. (Tom Williams/CQ-Roll Call, Inc via Getty Images)

The acting director added that "emotions are raw" within the agency right now, and he wants to "hear more" from the agent who wrote the email and described himself as a U.S. Marine as well as a 20-year veteran with the USSS. Rowe added that he is committed to reviewing things and being a "change agent."

When reached for comment, the Secret Service referred Fox News Digital to Rowe's testimony.

Rowe was also grilled on Monday by Sen. Mike Lee, R-Utah, who asked how it was possible that Trump was allowed on stage 17 minutes after reports of a suspicious person.

"No information regarding a weapon on the roof was ever passed to our personnel," Rowe said.

"How is that even possible?" Lee asked.

That information was "in local law enforcement channels but did not cross over and make it to Secret Service awareness," Rowe responded. "I think that they were in the midst of dealing with a very critical situation and they articulated that over the radio, as I understand it. However, it was never relayed over to us."

TRUMP ASSASSINATION ATTEMPT: FBI SAYS GUNMAN CLIMBED HVAC, TRAVERSED ROOFTOPS TO SHOOTING PERCH

The Butler Farm Show, site of a campaign rally for Republican presidential candidate former President Donald Trump, is seen Monday, July 15, 2024 in Butler, Pa. Trump was wounded on July 13 during an assassination attempt while speaking at the rally.  (AP Photo/Gene J. Puskar)

The USSS letter comes after the FBI on Monday morning told reporters in a conference call that Crooks accessed the roof of a building near former President Trump's rally in Butler using HVAC equipment and piping. 

Crooks then traversed multiple rooftops before he found his shooting position on top of a building owned by American Glass Research (AGR), located near the Butler Farm Show fairgrounds about 150 yards from where the former president spoke at his rally.

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On the day of the rally, Crooks parked his vehicle and flew a drone between about 3:50 p.m. and 4 p.m. about 200 yards from where the former president would be speaking on July 13. FBI Director Christopher Wray testified during a July 17 congressional hearing that Crooks had been at the rally site for about 70 minutes the morning of the assassination attempt. 

It is still unclear how Crooks evaded security even after being noticed by law enforcement approximately 90 minutes before shots rang out, but the FBI said more than 300 agents and staff are working "round the clock" to gather facts and put together a clearer timeline of Crooks' actions.