Rep. Chris Collins, R-N.Y., submitted a letter of resignation on Monday ahead of his expected guilty plea later this week to insider trading charges, Fox News has confirmed. It's an about-face for the embattled lawmaker, who pleaded not guilty earlier this month.

"I hearby submit my resignation effective immediately, September 30, 2019, as United States Representative of the 27th District of New York," Collins said in a lettter to New York Gov. Andrew Cuomo.

Collins' resignation came just hours after it was reported that there will be a "change of plea hearing" when he appears in a Manhattan courtroom on Tuesday. That appears to indicate that Collins, his son, Cameron, and his son’s prospective father-in-law, Stephen Zarsky, will plead guilty.

Collins originally pleaded not guilty to a slew of charges brought against him last year. He maintained his innocence when he was arraigned earlier this month on a superseding indictment that prosecutors hoped would speed up the case against the New York Republican.

NEW YORK REP. CHRISTOPHER COLLINS INDICTED ON INSIDER TRADING CHARGES

The superseding indictment against Collins streamlined the charges against him by keeping only five of the original eight securities fraud counts from the original indictment. The new indictment also dropped two of the original eight securities fraud charges against the congressman's son while leaving the remaining charges in place.

"The government has made these modifications in the original indictment in an effort to avoid unnecessary pretrial litigation that could delay the resolution of the matter," Geoffrey S. Berman, the U.S. attorney for the Southern District of New York, wrote in a recent letter to the judge in the case.

The fraud counts against Collins relate to securities of an Australian biotechnology company called Innate Immunotherapeutics; the 69-year-old congressman served on the board.

Prosecutors allege Collins passed along secrets to his son in June 2017. They say the son traded on the inside information and passed it to Zarsky. They added that Zarsky traded on it and tipped off at least three others.

According to the original indictment, Collins specifically got early word that a drug the company had developed for the treatment of multiple sclerosis wasn't performing well in a medical trial and passed the tip to his son. Prosecutors said the three avoided more than $768,000 in losses by trading ahead of the public announcement of the failed drug trials.

The advocacy group Public Citizen filed a request for an investigation of Collins' stock dealings with the Office of Congressional Ethics and the Securities and Exchange Commission in January 2017.

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The congressman, who has served New York's 27th District since 2013, surrendered to federal agents in Manhattan in August 2018.

Following the charges brought against Collins last year, then-House Speaker Paul Ryan removed Collins from his post on the House Energy and Commerce Committee and called the insider trading charges "a clear violation of the public trust."

Collins has a track record of publicly backing Trump, including being one of the first sitting members of Congress to endorse his White House candidacy. While he originally said last year that he would not seek reelection following the indictment against him, he reversed course and eventually defeated Democrat challenger Nate McMurray – albeit by a much narrower margin than expected, 49.1 percent to McMurray’s 48.8 percent.

Fox News' Chad Pergram and Marta Dhanis contributed to this report.