Quoting sources familiar with the investigation, The Post said Tuesday allegations that the freshman Democrat had groped "multiple" male staffers in his office date back at least a year.

The allegations center on a "a pattern of behavior and physical harassment," one source said.

Massa could not be reached for comment and nobody answered the telephone at his New York home or campaign office, the Post said. Massa stepped down Monday after saying he would not run for re-election.

The newspaper cited sources saying Ron Hikel, Massa's former deputy chief of staff, had given information about the allegations to the House Ethics Committee about three weeks ago. Hikel had sought advice from the office of House Majority Leader Steny Hoyer, D-Md., which urged him to report the allegations, the Post said. Hikel declined to comment.

Massa had said he had used "salty language" with staff and apologized for what he called an inappropriate comment to one staffer.

On Tuesday, Hoyer dismissed as "absurd" and "absolutely untrue" Massa's claim on a radio talk show that Democrats pushed him out of office over his opposition to the House healthcare bill.