Democratic leaders lambasted President Trump for pardoning his former national security adviser Michael Flynn on Wednesday, condemning the move as a "brazen" abuse of power. 

House Speaker Nancy Pelosi, D-Calif., said that Trump's act was one of "grave corruption" and said that Flynn "must be held accountable" for a "serious and dangerous breach of our national security." 

“President Trump’s pardoning of Michael Flynn, who twice pleaded guilty to lying to the FBI about his dealings with a foreign adversary, is an act of grave corruption and a brazen abuse of power," Pelosi said in a statement. "Trump is again using the pardon power to protect those who lie to cover up his wrongdoing."

Trump announced the decision Wednesday in a tweet after months of speculation that he would pardon his first national security adviser, who had pleaded guilty twice to knowingly making false statements to the FBI about a conversation he had during the presidential transition period with the then-Russian ambassador. 

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Flynn later worked to withdraw his guilty plea in January 2020. In May, the Justice Department (DOJ), after initially defending the prosecution, reversed its position and began looking to drop the charges against him. His legal case had since stalled, after U.S. District Court Judge Emet Sullivan resisted the DOJ's request and appointed a judge to determine whether Flynn should be held in criminal contempt for perjury.

"This 'Pardon of Innocence' is historic, sincerely appreciated & should never happen in our country again," Flynn, who resigned from his administration position in February 2017, tweeted on Thursday. "I will issue a personal statement later today...Thank you America. Happy Thanksgiving." 

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House Intelligence Chairman Adam Schiff, D-Calif., who played a key role in Trump's impeachment investigation in the House last year, said Flynn's pardon was in line with the president's repeated abuse of the pardon power to "reward friends and protect those who covered up for him."

"This time he pardons Michael Flynn, who lied to hide his dealings with the Russians. It’s no surprise that Trump would go out as he came in — Crooked to the end," Schiff tweeted.

House Judiciary Chairman Jerry Nadler, D-N.Y., echoed that sentiment, calling Flynn's pardon "undeserved," "unprincipled" and "one more stain" on Trump's "rapidly diminishing legacy." 

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"This pardon is part of a pattern. We saw it before, in the Roger Stone case — where President Trump granted clemency to protect an individual who might have implicated the president in criminal misconduct," he wrote in a statement. "We may see it again before President Trump finally leaves office. These actions are an abuse of power and fundamentally undermine the rule of law."