By Carol D. Leonnig – Tuesday, March 9, 2010; 5:01 PM

Former representative. Eric Massa (D-N.Y.) has been under investigation for allegations that he groped multiple male staffers working in his office, according to three sources familiar with the probe.

The allegations surrounding the former lawmaker date back at least a year, and involve “a pattern of behavior and physical harassment,” according to one source. The new claims of alleged groping contradict statements by Massa, who resigned his office on Monday after it became public that he was the subject of a House ethics committee investigation for possible harassment.

Massa had said that the allegations were limited to his use of “salty language” with his staff. He apologized for making some inappropriate comments and argued he was being unfairly vilified.

Days later, Massa accused the White House and Democratic congressional leaders of trying to oust him from office to improve their chances of passing health-care reform legislation – a charge that the House majority leader, Rep. Steny H. Hoyer (D-Md.), called “absurd.”

Massa could not be reached for comment Tuesday, and no one answered the phone at his campaign office or at his home in Corning, N.Y., where he lives with his wife, Beverly, and a son and daughter. Staff at his former congressional offices declined to relay messages to him and said they did not know how to reach him.

According to two sources familiar with the probe, Massa’s former deputy chief of staff Ron Hikel provided the information about the staffers’ allegations to the House ethics committee three weeks ago. Hikel had earlier sought advice from Hoyer’s office about brewing internal complaints, the sources said, and had been urged to report the allegations to the committee.

Hikel, reached at his home Tuesday, declined to comment on the ethics investigation.

Also on Tuesday, White House press secretary Robert Gibbs dismissed Massa’s charges of a conspiracy to force him from office as “silly and ridiculous” in an appearance on ABC’s “Good Morning America. He urged looking at Massa’s erratic and changing statements about why he was resigning office.

“Last week, he, on Wednesday, was having a recurrence of cancer. On Thursday, he was guilty of using salty language. On Friday, we learned he’s before the ethics committee to be investigated on charges of sexual harassment,” Gibbs said. “So, look, I think, clearly, his actions appear to be in the appropriate venue in the ethics committees to look at, but we’re focused not on crazy allegations but instead on making this system work for the American people rather than work for insurance companies.”

Research editor Alice Crites contributed to this report.