NEW YORK — Rep. Chris Collins is resigning from Congress and expected to plead guilty to insider-trading charges on Tuesday, following allegations last year that the Republican from New York schemed with his son to avoid significant losses on a biotechnology investment.

Collins, President Trump’s first congressional supporter, allegedly tipped off his son to confidential information about an Australian biotechnology company, Innate Immunotherapeutics, that he learned as a member of its board. Collins and several others used the information to avoid more than $700,000 in losses, according to prosecutors.

He is scheduled to change his plea Tuesday afternoon in a Manhattan federal court.

Collins’s son, Cameron, and another family member are scheduled to change their pleas on Thursday.

Collins sent a two-sentence resignation letter to New York Gov. Andrew M. Cuomo (D) on Monday. “I hereby submit my resignation effective immediately, September 30, 2019, as United States Representative of the 27th District of New York,” the letter said. He sent a similar letter to House Speaker Nancy Pelosi (D-Calif.).

The resignation will become effective after a letter is officially filed at a scheduled House session Tuesday.

Collins’s attorney did not respond to an email and phone call seeking comment.

Collins, who once called the charges against him “meritless,” has since 2013 represented New York’s 27th Congressional District, which encompasses suburban and rural areas stretching east of the Buffalo metropolitan area.

Collins won reelection last year after initially suspending his campaign, then reversing that decision despite pressure from Republicans to step aside and allow another GOP candidate on the ballot. Collins was sworn in for a fourth term in January but was not seated on any House committees pending resolution of his indictment.

Several candidates have announced campaigns to challenge Collins in 2020, including GOP state Sens. Chris Jacobs and Rob Ortt, as well as Democratic lawyer Nate McMurray, who came about 1,000 votes shy of unseating Collins last year. Should Collins resign, Cuomo would set a special election for the coming months.

Despite Collins’s close reelection race, the 27th District is considered reliably Republican — Trump won it by 24 points in 2016.

Collins was among Trump’s earliest endorsers and continued speaking out on his behalf after being indicted — including as recently as last week, when the congressman issued a statement criticizing Democrats’ announcement of a formal impeachment investigation of Trump. The White House and fellow Republicans, however, have kept their distance from Collins.

Collins was indicted in August 2018 and had been fighting the charges. Innate Immunotherapeutics was developing a new therapy for multiple sclerosis. Collins served on the company’s board of directors and was its largest shareholder, according to a federal indictment.

According to prosecutors, while at the June 2017 congressional picnic at the White House, Collins received an email from Innate Immunotherapeutics' chief executive alerting the company’s board that an eagerly anticipated drug trial had been a failure. Minutes later, Collins responded to the email: “Wow. Makes no sense. How are these results even possible???”

Collins immediately tried to contact his son, who owned millions of Innate Immunotherapeutics shares, according to the indictment. Within a few minutes, Collins and his son called each other six times before connecting and talking for six minutes. During that call, Collins told his son about the failed drug trial, according to the indictment, which cites phone and bank records as well as texts.

With that insider knowledge, Collins and his family were able to avoid significant losses before the news became public and the company’s stock price fell more than 90 percent, prosecutors allege.

It is unclear what specific charges Collins could plead guilty to and if he has a deal with prosecutors that will spare him time in prison. He is charged with multiple counts of securities and wire fraud and lying to the Federal Bureau of Investigations.

A spokesman for the U.S. Attorney’s office in New York declined to comment.

The Securities and Exchange Commission also filed charges against Collins.