Sen. Richard Blumenthal, D-Conn., predicted that Americans will be "shocked" and "appalled" when lawmakers release their interim report on the assassination attempt on former President Trump and the security failures of those involved in protecting the GOP presidential nominee. 

Acting U.S. Secret Service Director Ronald Rowe provided senators with an update Thursday on the investigation into the failed assassination in a closed-door meeting. 

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U.S. Secret Service Acting Director Ronald Rowe

U.S. Secret Service Acting Director Ronald Rowe testifies before a Joint Senate Committee on Homeland Security and Governmental Affairs and Senate Committee on the Judiciary hearing examining the security failures leading to the assassination attempt on former President Trump in Washington, D.C., on July 30. (AP Photo/Kevin Wolf)

"I think the American people are going to be shocked, astonished and appalled by what we will report to them about the failures by the Secret Service in this assassination attempt on the former president," Blumenthal told Fox News. "But I think they also ought to be appalled and astonished by the failure of the Department of Homeland Security to be more forthcoming, to be as candid and frank, as it should be to them in terms of providing information."

Blumenthal didn't go into specifics about what he learned from Thursday's meeting. Despite his statements, other lawmakers refused to comment on how the public may react to their report. 

"It will be coming out shortly. And it'll only be an interim report because there's a lot more information that we need to find," Sen. Gary Peters, D-Mich., told Fox News. "And we hope once this report comes out and we can get the additional information necessary to have a complete report of what happened, as well as steps of what we need to do in the future to make sure that this never happens."

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Pictures of the assassination attempt of Republican presidential candidate former President Donald Trump are displayed during the Republican National Convention

Pictures of the assassination attempt of former President Trump are displayed during the Republican National Convention in Milwaukee on July 18. (AP Photo/Jae C. Hong)

Sen. Ron Johnson, R-Wis., said lawmakers want to make sure the public understands that the report will be done in a bipartisan fashion. He said there was some frustration voiced with Rowe on Thursday. 

"So he's making the commitment to, you know, provide more information," Johnson said. "But we're hoping to get this preliminary report out before this work period. So again, we're on pretty tight time constraints. But again, it's important people realize we are dedicated to a bipartisan product."

The Secret Service has come under intense scrutiny over the security and communication lapses preceding the July 13 shooting of Trump during a campaign rally in Butler, Pennsylvania.

Assistant Director Michael Plati, of the agency's Office of Protective Operations, who led the section in control of planning for protection of Trump, President Biden, Vice President Kamala Harris, Ohio Sen. JD Vance and others, is ending his tenure there on Friday, his 27th anniversary at the agency.

Michael Plati

Michael Plati, U.S. Secret Service assistant director for the Office of Protective Operations, is set to retire. (United States Secret Service)

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The Secret Service said Plati wasn't asked to retire or resign, though sources involved at the highest levels of the internal investigation told Fox News he was encouraged to retire early.