Sources close to the Secret Service say Director Kimberly Cheatle has tendered her resignation one day after an incendiary congressional hearing marked by accusations of dereliction and her mea culpa for allowing an attempted assassination of former President Donald Trump.

NBC Homeland Security Correspondent Julia Ainsley was first to report on two sources who said that the director resigned Tuesday morning and that an official announcement would be coming later in the day. Cheatle previously declined to resign in an interview she gave just days after Trump was struck by a bullet while speaking at a rally in Butler, Pennsylvania. The shooting nearly became a constitutional crisis and prompted a reckoning among lawmakers about the state of today’s political dialogue as well a bipartisan calls for increased security around presidential candidates.

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The steady drip of revelations about how the Secret Service handled Trump’s presidential campaign may ultimately have contributed to Cheatle’s departure. Last week major outlets reported that the service declined previous requests to staff Trump following death threats he had received, and on Monday Cheatle attempted to deflect when challenged to state how many requests she had denied.

Instead, the director told Congressman Jim Jordan (R-OH) that the Secret Service often relied on partnerships with local law enforcement to fill gaps in its coverage, especially during election years. Sen. Josh Hawley (R-MO) was the first to report that the Secret Service had staffed President Trump with personnel who were not trained agents.

On Monday Sen. Chuck Grassley (R-IA) claimed to have produced evidence from an agency whistleblower showing that the Secret Service assigned three “post” officers to Trump’s Butler, Pennsylvania rally on July 13, or additional detail members responsible for securing a certain segment of the perimeter. In contrast, Jill Biden’s visit to Pittsburgh drew 12 post officers. The disclosure was uncovered as part of Sen. Grassley’s investigation into correspondence within the Secret Service about how to staff both Trump and Jill Biden, who were just 33 miles apart that day.

Specifically under investigation is how the Secret Service partnered with law enforcement organizations in and around Butler to establish a protective presence along the perimeter of the rally. Cheatle and a spokesman for the Secret Service both claimed that the area was under guard by local authorities but said during Monday’s hearing that the building where the gunman fired from was outside that zone, contradicting previous findings. Lawmakers are also seeking to understand why the Secret Service determined that an agent could not be placed on the roof of the building due to its sloped incline, which Cheatle said would have disrupted an agent’s ability to monitor Trump.

Earlier in the day, authorities reported seeing 20-year-old gunman Thomas Crooks canvassing the area where he later took the shot, though was not determined to be suspicious. During the rally, another local officer encountered Crooks crawling along the ground with a rangefinder and reported it to headquarters only for agents to find Crooks missing when they returned. The FBI is investing why another officer backed away from Crooks on the roof seconds before he fired at Trump, striking the former president’s ear before agents shot and killed him.

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