WASHINGTON » A congressional ethics watchdog body is investigating whether as many as eight House members may have improperly shifted their positions on a bill to overhaul financial regulations in return for campaign contributions.

The Office of Congressional Ethics, created by the House in 2008 to try to crack down on conflicts of interests and lobbying abuses, has asked several Washington lobbying groups for copies of e-mails and details on any meetings with the eight members.

It has also asked the members for information on political donations received before the House voted in December to approve the regulatory bill; negotiators are now working to resolve differences between the House measure and one passed by the Senate.

The eight House members, all of whom are on the Financial Services or Ways and Means committees, are John Campbell, R-Calif., Joseph Crowley, D-N.Y., Jeb Hensarling, R-Texas, Chris Lee, R-N.Y., Frank Lucas, R-Okla., Earl Pomeroy, D-N.D., Tom Price, R-Ga., and Mel Watt, D-N.C.

The five Republicans voted against the bill, while the three Democrats voted in favor.

The preliminary investigation, which started less than a month ago, could be abandoned long before any charges are filed. Of the 48 preliminary reviews the office has initiated since 2009, only 13 have resulted in a recommendation for a formal investigation by the House ethics committee, and so far, in only one case, has a member been even modestly reprimanded.

A letter that the office sent on June 1 to the financial industry lobbyists, a copy of which was obtained by The New York Times, asks for any correspondence between their office and the eight House members from January 2009 until this month.

At least some of the requests to the House members ask for information on contributions received from industry lobbyists or corporations from Dec. 2 to Dec. 11, 2009, the day the bill was passed.

A spokesman for the Office of Congressional Ethics declined to comment on the matter.

George Rasley, a spokesman for Hensarling, said the investigation, at least in Hensarling’s case, centered on an allegation raised by an unidentified party that political contributions might have influenced his opposition to the House bill, a claim he rejected as unfounded.

For the 10 days in question, federal election records show Hensarling received $6,500 in donations from political action committees of the Investment Company Institute, the Chubb Corporation, and Liberty Mutual Insurance. He also received a $1,000 donation from the political action committee run by Thompson and Knight, a law firm based in Dallas.

"The congressman publicly opposed major provisions of this legislation for almost six months before the time in question, he co-authored an alternative months earlier, he voted against it in committee, and he voted against it on the House floor," Rasley said.

One Congressional official said the details of the inquiry might have been leaked as part of an effort to embarrass the Office of Congressional Ethics. The news was first reported on Monday by The Hill, a Washington newspaper that covers Congress.

House members frequently have attacked the office for what they claim is its willingness to tarnish reputations, even if the allegations under investigation cannot be substantiated. Ethics watchdog groups have defended its work, saying the inquiries have brought to light conflicts of interests that otherwise might not have been disclosed.

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