For the past eight months, the House ethics committee has been without its top staffer and chief counsel, a vacancy that comes as the panel struggles to forge ahead on investigations of high-profile Democrats.

William O’Reilly, the panel’s former staff director, left the committee last summer and has not been replaced. But the committee is trying to launch an inquiry into the finances of Rep. Charles B. Rangel (D-N.Y.), chairman of the powerful Ways and Means Committee, and is under pressure from Republicans to launch a probe into lawmakers’ relationship with the PMA Group, the now-defunct lobbying firm.

All of this work is much more difficult without an expert staffer running things behind the scenes.

“It’s not an easy job to fill,” said Rob Walker, a former staff director for both the House and Senate ethics panels. “They have to be able to act in a nonpartisan matter and be perceived as being able to act in a nonpartisan matter. They have to know the House and ethics rules. And if the candidate worked in the House, he or she may not be seen as being able to act in a nonpartisan manner.”

An investigative subcommittee headed up by Reps. Gene Green (D-Texas) and Doc Hastings (R-Wash.) is in charge of the Rangel inquiry, but the full ethics committee will have to approve any findings from that subcommittee, including any potential sanctions of the veteran New York Democrat.

The PMA scandal is also unfolding as the ethics committee tries to work without its chief staffer. The FBI raided the firm’s offices in November, and it imploded afterward. Investigators are reportedly looking into alleged “straw man” donations to lawmakers from PMA lobbyists, including the former owner, Paul Magliocchetti, although no one has been charged in the case at this point.

Rep. Jeff Flake (R-Ariz.) has offered six privileged resolutions calling on the ethics panel to investigate PMA and its ties to members, but so far Democrats have defeated Flake’s resolutions. Reps. John P. Murtha (D-Pa.) and Peter Visclosky (D-Ind.) have attracted most of the attention as the PMA scandal has unfolded, but dozens of other lawmakers had ties to the firm as well.

The ethics committee has also been pressured to look into lawmaker ties to nonprofit firms, but there has been no movement on that front. Just recently, media reports have linked Reps. Alan Mollohan (D-W.Va.) and Joe Barton (R-Texas) to charities with questionable activities or operations.

In August, Kenyen Brown was appointed acting staff director and chief counsel for the ethics committee by Hastings and the late Rep. Stephanie Tubbs Jones (D-Ohio). Brown was a former staffer on the Senate Ethics Committee, as well as an assistant U.S. attorney and deputy district attorney in Alabama before he moved over to the House panel.

But Tubbs Jones’ sudden death on Aug. 20, 2008, forced Speaker Nancy Pelosi (D-Calif.) to seek a replacement in the chair, and Green filled in for the remainder of the 110th Congress. Pelosi then appointed Rep. Zoe Lofgren (D-Calif.) earlier this year, and Rep. Jo Bonner (R-Ala.) took over as the ranking member of the bipartisan committee.

Lofgren, Bonner and their top aides on the committee — Blake Chisam and Todd Ungerecht, respectively — are interviewing other candidates for the chief of staff post, and they are spreading their net wide, including advertising in Capitol Hill newspapers for potential candidates. These ads were still running as of last week.

So far, no one has been chosen for the position, which requires knowledge of how the House functions, expertise in ethics law, and the ability to manage staff and political pressures that inevitably come with the top ethics staff job. House insiders thought the post would be filled before the House adjourned for the two-week Easter recess, but indications are that the search may continue for some time.

Brown did not return calls seeking comment on the staff director search.

Some ethics experts, though, cautioned that it was better for both the committee and the House as a whole if Lofgren and Bonner conducted a thorough vetting process, rather than making the wrong choice for the difficult post.

The staff director has to referee sometimes fiercely partisan battles inside the committee itself and then deal with blowback from party leaders when the panel’s actions turn controversial.

There is also intense media scrutiny of the secretive committee’s work, and the new Office of Congressional Ethics — finally up and running a year after its approval by the House — will place new demands on the ethics panel.

In addition to finding a new staff director, the ethics committee has lost other senior aides in recent months, and it faces new requirements on training and education for members and congressional aides.

“It’s more important that they take their time and get this right than meet some deadline,” said Ted Van Der Meid, former staff director for the ethics committee. Van Der Meid also served as counsel to former Speaker Dennis Hastert (R-Ill.).

“It has to be someone they agree on, and it should be,” Van Der Meid added.

Whomever is chosen for the top ethics committee job will immediately have to deal with the Rangel investigation, which is as complex and thorny as they come. The committee announced on Sept. 24 that it was beginning a probe following reports that Rangel had several rent-controlled apartments in a Harlem luxury building, used official letterhead to help raise money for the Charles B. Rangel Center for Public Service at City College in New York and had failed to pay income taxes on a resort home in the Dominican Republic.

Pelosi initially stated that she thought the investigation would be over by the time the 111th Congress began in January, but the investigation was expanded after The New York Times reported that Rangel had reportedly done a legislative favor for a big donor to the Rangel Center.

Rangel has denied any wrongdoing, but Republicans have repeatedly called on him to step down from his Ways and Means Committee post while the investigation, now in its seventh month, continues.