[What you need to know to start the day: Get New York Today in your inbox.]

Representative Chris Collins, a fourth-term Republican from Western New York who narrowly won re-election last year despite fighting federal securities fraud charges, resigned on Monday in advance of an expected guilty plea.

Mr. Collins, 69, the first sitting member of Congress to endorse President Trump in 2016, had been accused of using private information about a drug company in which he was invested to help his son and others avoid financial losses.

Mr. Collins was to be tried in February along with his son, Cameron Collins, 26, and a third man, all of whom had pleaded not guilty. A document filed in Federal District Court in Manhattan on Monday said there would be a “change of plea” hearing on Tuesday for all three men, although the filing did not indicate what charges the men would be pleading guilty to.

The men were facing charges of conspiracy, securities and wire fraud and making false statements.

There is no law that requires members of Congress to give up their seats when convicted of a felony, though House rules dictate that the member not vote after their convictions.

Speaker Nancy Pelosi’s office received a letter of resignation from Mr. Collins, a spokesman for Ms. Pelosi confirmed on Monday, and his resignation will be effective once the letter is filed during the House’s pro forma session on Tuesday. A state official confirmed that Gov. Andrew M. Cuomo had also received Mr. Collins’s letter.

With Mr. Collins’s resignation, Governor Cuomo, a Democrat, will have to call a special election to fill the seat.

A spokeswoman for Mr. Collins did not immediately return a request for comment, nor did lawyers for him and his son. The United States attorney’s office for the Southern District of New York declined to comment.

Mr. Collins had not said whether he would seek another term, though he transferred $500,000 of his own money into his campaign fund in June. Aside from that money, he had raised just $14,000 in the first six months of this year.

In 2017, by contrast, Mr. Collins received more than $500,000 in contributions in the same period.

Contenders in both parties had already stepped up to challenge him. Nate McMurray, the Democratic town supervisor of Grand Island, which is just north of Buffalo, has declared his plans to run again.

Mr. McMurray lost by less than half a percentage point last year, even though the district had voted for President Trump over Hillary Clinton by a margin of almost 25 points.

Several Republicans had also announced plans to run in the primary election: two state senators, Chris Jacobs and Robert Ortt, as well as Beth Parlato, a lawyer and former judge. Republican Party officials, including the state party’s chairman, Nick Langworthy, had suggested that they would like to see a candidate other than Mr. Collins run.

Prosecutors had said that Mr. Collins was at the Congressional Picnic on the South Lawn of the White House on June 22, 2017, when he received an email from the chief executive of an Australia-based drug maker, Innate Immunotherapeutics. Mr. Collins was a member of the company’s board of directors and one of its largest shareholders, owning nearly 17 percent of its stock, the authorities said.

In the email, the chief executive, Simon Wilkinson, informed Mr. Collins and other board members that he had “extremely bad news”: An experimental drug that the company was developing to treat multiple sclerosis had just failed a critical clinic test.

“Wow,” Mr. Collins wrote back, according to a federal indictment. “Makes no sense. How are these results even possible???”

Mr. Collins then repeatedly called his son, reaching him on the seventh try, and told him about the failed drug trial — information that was not public — in anticipation that his son “would use it to trade and tip others,” the indictment said. Cameron Collins passed the tip to others, including Stephen Zarsky, his fiancée’s father, the authorities said.

In the following days, by selling Innate stock before news of the failed drug trial became public, Cameron Collins was able to avoid losses of about $570,000 and Mr. Zarsky of about $144,000, the authorities said. The congressman did not make any trades, the government said.

Mr. Collins was stripped of his seat on the House’s Energy and Commerce Committee after his indictment last August. Paul Ryan, then the Republican House speaker, in announcing the punishment, also called for the House Ethics Committee to investigate the allegations.

Days after the indictment, Mr. Collins suspended his 2018 re-election bid. But a month later, he reversed course and resumed campaigning, blindsiding party leaders.

Emily Cochrane contributed reporting from Washington. Susan C. Beachy contributed research.

(adsbygoogle = window.adsbygoogle || []).push({});
(adsbygoogle = window.adsbygoogle || []).push({});