The Democratic candidate in the race, Nate McMurray, the town supervisor of Grand Island, had only $80,000 in his campaign account when the indictment was announced — far less than is typically needed to wage an aggressive challenge.
Mr. McMurray had not been the preferred candidate of Democratic leaders in New York, led by Gov. Andrew M. Cuomo, who had recruited Lt. Gov. Kathy Hochul for the seat. She declined and instead ran for re-election.
One Republican said the party hoped to run Stefan Mychajliw, the Erie County comptroller, to replace Mr. Collins, though others are also expected to jockey for the party’s nomination. In a preview of what will most likely be a polarized and partisan race over the next three months, Mr. Mychajliw called Mr. McMurray “radical” three times in a four-paragraph statement.
If Republicans can successfully remove Mr. Collins, whoever they replace him with would have an edge given the district’s conservative tilt. Even after the indictment of Mr. Collins, nonpartisan political handicappers said the seat would be a steep climb for Democrats.
“I respect Chris Collins’s decision to step down while he faces these serious allegations. As I’ve said before, Congress must hold ourselves to the highest possible standard,” Representative Steve Stivers, an Ohio Republican and the chairman of the House Republican campaign committee, said in a statement.
Democrats hope to use the details of the charges against Mr. Collins outlined in the indictment to help paint both the Trump administration and the Republican-controlled Congress with the broad brush of a “culture of corruption.”
In announcing the indictment, Geoffrey S. Berman, the United States attorney in Manhattan, said, “Congressman Collins, who by virtue of his office helps write the laws of our nation, acted as if the law did not apply to him.”