Democrats on the House Judiciary Committee called on DOJ Inspector General Michael Horowitz Friday to investigate Attorney General William Barr's “improper political preference” after the Justice Department moved to drop its case against former national security adviser Michael Flynn.

The committee, led by Chairman Jerrold Nadler, D-N.Y., said that the former national security adviser had already been offered a “generous” plea deal under Special Counsel Robert Mueller, allowing him to plead guilty to lying to the FBI but “avoid prosecution for other serious alleged crimes.”

Flynn for months has been trying to withdraw his guilty plea, arguing that he was “pressured” into pleading guilty to making materially false statements to the FBI in the Russia probe. Newly declassified documents revealed agents discussed their motivations for interviewing him in the Russia probe – questioning whether they wanted to "get him to lie" so he'd be fired or prosecuted, or get him to admit wrongdoing.

MCENANY AT WHITE HOUSE BRIEFING ACCUSES FBI OF TRYING TO 'MANUFACTURE' A CRIME AGAINST FLYNN IN 2017

The letter from the Democrats also suggested possible Hatch Act violations. “Of course, the Hatch Act prohibits Department of Justice employees from engaging in partisan political activities in the course of official business,” the letter said.

"Federal law also disqualifies any DOJ employee ‘from participation in a particular investigation or prosecution if such participation may result in a personal, financial, or political conflict of interest, or the appearance thereof.’ Simply put, the Attorney General is prohibited from putting his thumb on the scale in favor of the President, time and time again," it continued.

DOJ DROPS CASE AGAINST FLYNN, IN WAKE OF INTERNAL MEMO RELEASE

The committee pointed to other instances where they believed Barr had shown political bias. It cited a March 2019 summary of the Mueller report Barr had sent to the House and Senate Judiciary committees about the findings of Trump and his associates, saying the Special Counsel later said Barr’s memo “sought to create ‘public confusion’ and threatened ‘to undermine a central purpose for which the Department appointed the Special Counsel.’”

It also accused the Justice Department of “quietly” closing its investigation into campaign finance crimes allegedly committed by Trump and his former attorney Michael Cohen.

Cohen is currently serving a three-year prison term in upstate New York for the campaign finance violations, as well as other offenses including bank and tax fraud, but the investigation into hush money payments arranged by Michael Cohen -- which Cohen claims were at Trump’s direction -- came to an end last July.

The letter alleged the Justice Department “abruptly reversed course” in February 2020 and sought a more lenient sentence for Trump confidante Roger Stone, writing, “As with the Flynn case, the Department appeared to have reacted to a series of public statements from the president.”

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The judge presiding over the Stone case, U.S. District Judge Amy Berman Jackson, agreed with Justice Department leadership that her original sentence, 87 to 108 months, was "greater than necessary” after Barr intervened, overruling and scaling back the proposed prison sentence.

Stone was sentenced to 40 months in prison on charges of obstruction, witness tampering and making false statements to Congress on charges that stemmed from former Special Counsel Robert Mueller’s investigation.

On Thursday, Barr called the Justice Department’s decision to drop the case against Flynn his “duty” – saying he wanted to “restore confidence in the system.”

“I want to make sure that we restore confidence in the system. There's only one standard of justice,” Barr told CBS News. “And, I believe that ... justice, in this case, requires dismissing the charges against General Flynn.”