Secret Service chief Kimberly Cheatle admitted Monday that the near-assassination of Donald Trump was the agency’s “most significant operational failure’’ in decades — but still gave agents an “A’’ for that day.

The embattled director’s comments at a congressional hearing prompted even more Democratic lawmakers to join their Republican colleagues in demanding she resign — while the Cheatle refused and dug her heels in. 

“The Secret Service’s solemn mission is to protect our nation’s leaders. On July 13th, we failed,” Cheatle told members of the House Oversight Committee probing the horribly botched security that day. 

“As the director of the United States Secret Service, I take full responsibility for any security lapse,” she claimed.

But House Oversight Committee Chairman James Comer (R-Ky.) noted that she has defied demands for her to take responsibility and step down — and revealed that he and the top Democrat on the panel, Rep. Jamie Raskin (D-Md.), are now jointly calling for her resignation.

Rep. Ro Khanna (D-Calif.) referenced Stuart Knight, the head of the Secret Service under President Ronald Reagan, after Cheatle called her failure the greatest since the Gipper’s near-assassination in 1981.

“Do you know what Stuart Knight did?” Khanna asked Cheatle, referring to the aftermath of Reagan’s near-assassination.

“He remained on duty,” Cheatle responded.

“He resigned,” Khanna corrected her. “If you have an assassination attempt on a president, a former president or a candidate, you need to resign.

“That’s what Stuart Knight did. He was a Republican appointee, and he took responsibility,” the Dem said.

Pennsylvania Rep. Brendan Boyle became the first Democrat to call for Cheatle’s resignation two days ago, citing “unacceptable operational failures.”

Lawmakers from both sides of the aisle Monday also balked at the Secret Service director and her agency divulging more to the media about the shooting than to Congress.

“You answered more questions with an ABC reporter than you have with members of Congress,” Comer said about halfway through the hearing, noting earlier that his panel had to subpoena her for testimony.

Rep. Nancy Mace (R-SC) lost her temper and cussed at Cheatle for declining to provide to the committee a list of law enforcement personnel present as well as audio and video recordings of the incident.

“You’re full of sh-t today!” Mace erupted.

Rep. Jared Moskowitz (D-Fla.) even compared Cheatle’s performance in the hearing to that of the Ivy League presidents who resigned over their failures to quell antisemitism on campus.

“This is where this is headed,” Moskowitz said, adding pressure on her to resign.

During Monday’s proceeding, Cheatle offered her “sincerest condolences to the family of Corey Comperatore,” the father and volunteer fire chief who was killed in the shooting of Trump, and wished a “speedy recovery” to the two other crowd-goers who were wounded, David Dutch and James Copenhaver.

Cheatle claimed that “the level of security provided for the former president increased well before the campaign and has been steadily increasing as threats evolve” — contradicting whistleblower testimony about the “little resources” available to the agency after a NATO summit in Washington, DC.

The whistleblowers informed the House Judiciary Committee last week that Secret Service Special Agent in Charge Tim Burke acknowledged the depleted resources at a July 8 meeting with the FBI and other law-enforcement partners — five days before the Butler Farm Show rally where Trump was grazed in the right ear.

Thomas Matthew Crooks, 20, was able to evade Secret Service and local Butler police officers before taking aim and firing multiple shots at Trump from the roof of the AGR International Inc. building — a “vulnerability” acknowledged beforehand by the agency that sat just 130 yards from the main stage at the campaign event.

A local police counter-sniper team from Butler had been stationed inside the manufacturing facility building — but never caught Crooks  eyeing the main stage through a rangefinder scope and setting up his sniper’s perch above — with one officer confronting but failing to stop the gunman before he opened fire.

“At the outset, let me state unequivocally: Nothing I have said previously should be interpreted to place blame for this failure on our federal, state, and local law enforcement partners who supported the Secret Service in Butler, Pennsylvania,” Cheatle said Monday. “We could not do our job without them.”

But Oversight Committee ranking member Jamie Raskin (D-Md.) shot back in disbelief, “How can a 20-year-old with his father’s AR-15 assault weapon climb onto a roof with a direct, 150-yard line of sight to the speaker’s podium, without the Secret Service or local police stopping him?” 

Cheatle replied, “We are nine days out from this event.

“And I would like to know those answers as well,” she said.

In other exchanges with lawmakers, Cheatle also acknowledged that she had yet to visit the site of the shooting — whereas Crooks had scoped out the rally location with a drone.

She gave the Secret Service agents who threw themselves on top of Trump and fatally shot Crooks an “A” letter grade — and said “none” in the agency had lost their jobs.

But Cheatle also suggested the agency needs “to be adequately resourced” and grow its $3.1 billion budget for all protectees, adding that she was “striving toward” hiring at least 1,500 employees.

Judiciary Committee Chairman Jim Jordan (R-Ohio) was the first to grill Cheatle about contradictory statements the Secret Service has made since the shooting, including about having snubbed earlier requests from the Trump campaign for enhanced security at rallies, according to the Washington Post.

“Were you guessing or lying when you said you didn’t turn down a request from President Trump’s detail?” Jordan pressed, referencing a Secret Service spokesman’s admission of the snubbed requests.

Cheatle responded, “Neither, Sir.

“Assets that were requested for that day were given,” and “a denial of a request is not equal [to] a vulnerability,” she said.

Cheatle said during questioning that the building from where Crooks opened fire was “outside the perimeter” of Secret Service protection — and that the reason for her agency not having counter-snipers on the building was because the agency prefers to have “sterile” rather than “sloped” roofs.

“There was a plan in place to provide overwatch,” she also said, without clarifying how “three concentric rings of protection” were enforced during the rally but confirming that the rings excluded the factory building.

“Does the secret service have a written policy you could share with us about sloped roofs?” mocked Rep. Pat Fallon (R-Texas), who called attention to Secret Service putting counter-snipers on a 312-degree sloped roof that was “steeper” than the 112-degree roof of the AGR building.

“No,” Cheatle acknowledged.

“You can build a ramp for a wheelchair on a 112 [degree] roof,” Fallon went on, “so these are nothing but pathetic excuses, and they make no sense and are a bunch of cow dung.”

“You should be fired immediately and go back to guarding Doritos!” he lambasted her, apparently referring to her time at the helm of global security for PepsiCo, which owns Doritos.

She declined to give any responses about how Crooks climbed onto the building’s roof, how he could be labeled “suspicious” without being considered a “threat”  until moments before opening fire — or how the security footprint lacked preparations for a known threat of assassination from Iran.

“Director Cheatle, is an Iranian assassin more capable than a 20-year-old?” Intelligence Committee chairman Mike Turner (R-Ohio) fumed, adding that FBI Director Christopher Wray confided that he was “shocked” about the security breaches.

“Sir, I think we’ve acknowledged that there were gaps and a failure that day,” Cheatle responded, later telling another Intelligence panel member that there is no indication Crooks acted in concert with a foreign state.

“Director Cheatle, because Donald Trump is alive — and thank God he is — you look incompetent,” Turner fired back. “If Donald Trump had been killed, you’d look culpable.

“The threat was identified before he took the stage, and the shooter was only killed after,” he added. “Not only should you resign, if you refuse to do so, President Biden needs to fire you.”

Far-right Rep. Marjorie Taylor Greene (R-Ga.) went further and suggested, without evidence, that there may have been an order given to “stand down” given the egregious lapses in security.

“Was there a stand-down order Ms. Cheatle? Was there a conspiracy to kill President Trump?” Greene floated.

“Absolutely not,” Cheatle said.

“Then how did this happen, and how are you still sitting here and not turning in your letter of resignation?” Greene replied.

Fallon told Cheatle he had recreated the shooting in Savoy, Texas, over the weekend and scored “15 out of 16 kill shots” while “lying prone on a sloped roof at 130 yards at 6:30 at night.

“It is a miracle President Trump wasn’t killed,” he shouted.

Fellow Texas GOP Rep. Michael Cloud said at another point, “The thing that you’ve said so far is that you want to make sure that this never happens again.

“The thing is everyone in America knows that’s not the job description that you’re tasked with; the job description that you’re tasked with is to make sure that it never happens — period,” he concluded.

Rep. Virginia Foxx of North Carolina and several other GOP lawmakers prodded Cheatle as to how she rose through the ranks of the Secret Service, with Foxx specifically referencing The Post’s report about first lady Jill Biden and her top adviser Anthony Bernal lobbying on Cheatle’s behalf.

“I think that I am the best person to lead the Secret Service at this time,” Cheatle responded, dodging Foxx’s question.

Rep. Tim Burchett (R-Tenn.) and others also questioned whether her appointment had been the result of a broader Diversity, Equity and Inclusion (DEI) initiative pushed by the Biden administration.

“Ma’am, you are a DEI horror story,” Burchett said bluntly.

The FBI and DHS’ Office of the Inspector General are investigating the Trump shooting, and Cheatle pledged to “fully” cooperate with both probes.