US Representative Bob Ney, a Republican from Ohio, resigned from Congress on Friday, three weeks after he pleaded guilty to a corruption scandal and four days before the midterm legislative elections.
Ney sent a letter of resignation to House Speaker Dennis Hastert, news reports said.
He was the first lawmaker to have confessed to crimes in a federal investigation into the scandal that centered on former lobbyist Jack Abramoff, which reportedly might implicate as many as 20 lawmakers.
The Ohio congressman, 52, had acknowledged taking money, gifts and favors in return for official actions on behalf of Abramoff and his clients.
Ney, who was first elected to Congress in 1994, had been pressed by fellow Republicans to resign after pleading guilty.
He faced a maximum of 10 years in prison if convicted, and the sentencing was set for Jan. 19 next year.
Abramoff and several of his associates have pleaded guilty to conspiracy, fraud and tax evasion charges in an influence-peddling scandal, and are cooperating in the corruption investigation.
Abramoff was sentenced in March to five years and 10 months in prison in a fraud case concerning the purchase of a gambling fleet in Florida.