The leaders of Congress' ethics committees are not committing to any investigation of misconduct despite the growing revelations about the favors that lobbyist Jack Abramoff won for clients and the largesse he arranged for lawmakers.

The committees, for now, are poised to remain on the sidelines.

The House committee, stymied by partisan disagreements, launched no investigations in 2005 even after former House Majority Leader Tom DeLay, R-Texas, requested an inquiry into his foreign travel arranged by Abramoff.

The lack of commitment to investigate issues about lawmakers' conduct with Abramoff, his lobbying team and his clients is raising anew the question of whether Congress adequately can discipline its own.

"There have always been questions about whether Congress can police itself," said Kathleen Clark, a law professor at Washington University in St. Louis who specializes in ethics. "The situation in the House removes all doubt. The House is not policing itself."

The Associated Press asked the four lawmakers who lead the ethics committees whether they would make a commitment to investigate ethical wrongdoing if, as expected, the information Abramoff supplies in a plea agreement exposes misconduct by a number of members of Congress. Each of the four -- two Republicans and two Democrats -- declined, through his spokesmen, to do so.

The House Committee on Standards of Official Conduct is headed by Rep. Doc Hastings, R-Wash.; the top Democrat is Rep. Alan Mollohan of West Virginia.

The Senate Select Committee on Ethics is led by Sen. George Voinovich, R-Ohio; the ranking Democrat is Sen. Tim Johnson of South Dakota.

While the committees have an equal number of Democrats and Republicans, forging a bipartisanship consensus in ethics investigations often has proved difficult.

After the House levied a $300,000 fine against former Speaker Newt Gingrich, R-Ga., for ethical violations in 1997 -- payment for part of the cost of investigating his conduct -- weary members of both parties declared an ethics truce. For several years, there were no major cases for several years.

The House committee revived itself in 2004, admonishing DeLay on three separate issues. The House Republican leadership reacted by refusing to extend the term of the chairman at that time, Rep. Joel Hefley, R-Colo. He had asked to stay on.

Last year, Hastings and Mollohan feuded for months over investigative rules, and then for additional months over the composition of the staff. The entire year was gone before the leaders finally chose the committee's top staff member; he started work only recently.

Abramoff pleaded guilty this month to conspiracy, tax evasion and mail fraud in Washington and to additional charges in Miami. He has agreed to cooperate with prosecutors.

The committees traditionally defer to prosecutors and do not interfere with criminal investigations. But they can investigate violations of standards of conduct that are separate from criminal violations.

Committee actions can range from a critical letter to recommendations of serious punishment by the full House -- all the way to expulsion.

The Abramoff criminal inquiry raises numerous issues. Lawmakers, for instance, are prohibited from accepting trips from lobbyists.

One way Abramoff lavished favors on lawmakers was through free travel that he arranged through nonprofit organizations that got money from the lobbyist's clients. DeLay has said he was unaware that Abramoff may have paid for some of his travel.

More than four dozen lawmakers -- from House Speaker Dennis Hastert, R-Ill., to Sen. Byron Dorgan, D-N.D. -- sent to federal agencies letters that were favorable to Abramoff clients or took official actions in Congress to help them.

Around the same time, those lawmakers received large political donations or used Abramoff's skybox or restaurant for fundraising. Some lawmakers didn't provide reimbursement until years later.

Ethics watchdog groups have written the committees alleging those activities violate congressional ethics standards that require lawmakers to avoid even the appearance of a conflict of interest.

Congress' response to the budding scandal so far, especially in the House, has been a flurry of proposals to write new laws to control lobbyists' relations with lawmakers. Some experts believe that without an investigation that can lead to discipline, ethics violators get a free pass.

"You have to publicly reprimand someone," said Judy Nadler, the former mayor of Santa Clara, Calif., and now a senior fellow at Santa Clara University. "If there are no consequences, things will not change. This is drive-by ethics."

Former Sen. Warren Rudman, a Republican who served on the Senate ethics committee, said, "The amount of politics that intruded into the House committee is discouraging."

Rudman said the ethics leaders have an obligation to follow up on any potential violations of standards of conduct. "It would be impossible not to address some of these issues," said Rudman, who served during the Keating Five investigation that suffered through partisanship in the Senate panel.

That investigation had similarities to the Abramoff case. It involved donations to five senators from a savings and loan operator, who persuaded the lawmakers to intervene with federal regulators on his behalf. The timing of the donations and official actions was a key issue with both the Keating Five and the Abramoff cases.

Andrew Kohut, president of the Pew Research Center for the People & the Press, said the Abramoff case is "likely to raise the issue of how well Congress does in keeping track of its own behavior."

But he said the public will not really get interested until more lawmakers are publicly named in the criminal investigation.