An ethics watchdog wants Congress to investigate the chairman of the House Financial Services Committee after reports that his aides pressured a mutual fund trade group to hire a Republican lobbyist.

Common Cause asked House Ethics Committee Chairman Joel Hefley on Tuesday to look into a report that Michael Oxley's aides linked their request to a committee probe into whether mutual funds are overcharging not providing customers with enough information.

Oxley spokeswoman Peggy Peterson denied her boss would ever consider backing off an investigation. "Rumors of some quid pro quo are exactly that, rumors," she said.

Common Cause President Don Simon said the actions, if true, were "an unconscionable abuse of authority."

"No member should be permitted to use the official power of his or her office to inflict punishment or reward behavior on a partisan basis," he said.

Ethics rules prohibit members of Congress from using their power to benefit people because of their party affiliation or forcing people to provide benefits, financial or otherwise.

Rep. Stony Hoyer, D-Md. said Democrats also plan to discuss this week whether they should file a formal complaint with the Ethics Committee. The committee would be required to address a complaint from a lawmaker; it may ignore requests from outside parties.

If lobbyists were enticed by promises of legislative advantages or disadvantages, "I think that may be both unethical and may border on being criminal," said Hoyer, the House's second-ranking Democrat.

An ethics complaint against Oxley could ruin a fragile truce in the House, where ethics charges rarely have been filed between parties, said House Majority Leader Tom Delay, R-Texas.

"I find very dangerous for the comity of the House for people to play politics by filing ethics charges that have no basis to be filed or no foundation," Delay told reporters.

The Washington Post on Feb. 15 reported that Oxley and his staffers were pressuring the Investment Company Institute, a consortium of mutual fund companies, to hire a Republican to replace or work with its top lobbyist, Julie Domenick, a Democrat closely associated with the party's most senior member in the House, Michigan Rep. John Dingell.

Anonymous sources were quoted by the newspaper as saying that Oxley and his aides delivered a strong message that if Domenick was replaced, the industry might enjoy greater access to and less scrutiny from the committee.

ICI spokeswoman Elizabeth Powell refused to comment on whether her group had received in pressure from Oxley or his aides.