House Minority Leader Robert H. Michel (R-Ill.) yesterday urged Rep. Donald E. "Buz" Lukens (R-Ohio) to resign or risk expulsion and the loss of his pension because of allegations that Lukens sexually harassed a congressional employee. A well-placed House Republican said last night that he expects Lukens to announce his resignation as early as today.

House GOP sources, who asked not to be identified, said Michel had urged Lukens to "do the right thing" and resign for the good of the institution. Michel reportedly told Lukens that if he does not resign the House might vote to expel him, resulting in the loss of his congressional pension.

Lukens, 59, who was convicted last year of a misdemeanor sex offense involving a minor, was scheduled to appear before the House ethics committee yesterday to face questioning on the new allegations. But at Lukens' request, the panel delayed his appearance until today.

The committee abruptly reopened its investigation into Lukens after the new allegations surfaced over the weekend. The earlier investigation, which stemmed from Lukens's conviction on the sex charge, was suspended after the Ohio Republican lost his bid for reelection last May in a GOP primary contest.

According to the new allegations, Lukens fondled and propositioned a Capitol Hill elevator operator. Lukens has been unavailable for comment on the charges.