WASHINGTON -- The House Democratic campaign chief said Wednesday the ethics committee has ended an investigation of former Rep. Eric Massa, but the freshman's alleged harassment of his staff members -- with possible sexual overtones -- could spell continuing trouble for the party.

Rep. Chris Van Hollen, D-Md., the campaign chairman, acknowledged that the end of an investigation into the New York Democrat's possible rule-breaking may not end the matter.

"When he resigned his seat, clearly the complaints filed with the ethics committee went away," Van Hollen said on an ABC News webcast.

He quickly added, "There may be other forums" for staff members who complained about Massa to pursue the matter.

Republicans are increasingly making an issue of the ethical conduct of Democrats, mindful that Republican ethical misconduct was one reason the GOP lost control of the House in the 2006 elections.

As the campaign unfolded that year, so did details that Republican leaders took no action after learning then-Rep. Mark Foley, R-Fla., sent sexually suggestive messages to former male pages.

When the complaints about Massa reached Majority Leader Steny Hoyer this month, he demanded that Massa's staff report the conduct within two days to the ethics committee. If not, Hoyer said he would make the report.

Republicans are clearly hoping it may turn out that some Democrats knew of Massa's alleged harassment. There is no evidence at this point that they did.

However a Democratic leadership aide, who was not authorized to be quoted, confirmed Wednesday night that in October, Massa's chief of staff met with a staff member in Speaker Nancy Pelosi's office to discuss problems with the lawmaker.

The Massa aide pointed out a negative story about the lawmaker in his hometown newspaper that described Massa's living arrangements with staff members. The Massa aide told the speaker's office that he asked the congressman, who is married, to move out.

Massa's aide also discussed Massa's use of strong language and the way he ran his office.

Pelosi's spokesman, Brendan Daly, said the harassment allegations didn't surface until last month.

"In February, when serious allegations against Mr. Massa were brought to the attention of leader Hoyer and a member of our staff for the first time, the staff concurred that an ethics investigation was the proper course of action."

Republican leader John Boehner said he didn't expect the matter to end anytime soon.

"There are an awful lot of questions surrounding the Eric Massa case and his resignation, and at this point, there are a lot more questions than answers, and I would hope that we would get to the bottom of these questions," he said.

The Massa case follows an ethics committee report that a Democratic kingpin, Rep. Charles Rangel, broke House gift rules when he accepted corporate money to attend two conferences in the Caribbean.

Rangel, a veteran New York congressman, stepped aside as chairman of the tax-writing Ways and Means Committee until the ethics committee resolves a separate investigation of his fundraising and finances.

Massa, a freshman lawmaker, resigned Monday. He gave contradictory explanations for his behavior in TV interviews Tuesday night, acknowledging that he groped a male staffer in a nonsexual way but later denied any groping. Massa also recalled wrestling with male staffers at his 50th birthday party and tickling one of them.