Rep. Donald E. "Buz" Lukens (R-Ohio) resigned from Congress yesterday rather than face an ethics committee investigation into new charges of sexual misconduct that could have led to his expulsion.

In a one-sentence letter to Ohio Gov. Richard F. Celeste (D), Lukens, 59, said he was relinquishing his congressional seat "for the good of the Congress and the integrity of the institution." Copies of the letter were transmitted to congressional leaders, and the resignation announcement was read on the House floor.

Lukens's resignation, a few days after he was accused of fondling a female elevator operator in the Capitol, ends an embarrassing episode for a Congress that already was beset with ethics problems and a budget impasse that made it the subject of criticism and ridicule.

Senior GOP leaders had urged Lukens to resign over the latest incident, which occurred a year and a half after he was convicted by an Ohio court of a misdemeanor sex offense involving a teenage girl. The Ohio lawmaker lost his primary election bid last May, so his resignation cuts short his tenure by only a little over two months.

Responding quickly to the latest allegation against Lukens, the House Committee on Standards of Official Conduct said Monday it would reopen and expand an investigation stemming from his conviction on the sex charge. That probe had been shelved following Lukens's primary loss. In addition, sources said House Minority Leader Robert H. Michel (R-Ill.) pointedly warned Lukens that he risked expulsion if he did not resign.

Lukens is the fourth House member to resign during the 101st Congress because of ethics problems. Last year, Speaker Jim Wright (D-Tex.) and Majority Whip Tony Coelho (D-Calif.) resigned in the face of questioning about their financial dealings. Robert Garcia (D-N.Y.) resigned in January after his extortion and conspiracy conviction, later overturned, in the Wedtech scandal.

A conservative lawmaker from southwestern Ohio, Lukens was once a rising GOP star in Ohio politics. He was elected to the House in 1966, but did not seek reelection in 1970 in an unsuccessful effort to win the gubernatorial nomination. He returned to the House in 1987.

In February 1989, a Columbus television station aired a covertly taped meeting between Lukens and a woman who said the lawmaker had paid to have sex with her daughter. The tape suggested that Lukens tried to buy the woman's silence with an offer of a government job.

Lukens was subsequently convicted for contributing to the unruliness and delinquency of a minor, sentenced to 30 days in jail and fined $500. He lost his first appeal in that case and is appealing to the Ohio Supreme Court.

Following his conviction, Lukens was urged by Ohio GOP officials to resign from the House. He refused, but was trounced in the primary.