Topeka ? The U.S. House ethics committee is extending an investigation of Congressman Todd Tiahrt’s involvement in political donations and defense appropriation earmarks secured for clients of a Washington lobby firm raided by federal agents.

Tiahrt and Rep. Peter Visclosky, D-Ind., are subject of an inquiry by the Committee on Standards of Official Conduct, which is looking into activities of the now-defunct lobbying firm known as PMA Group. This House ethics panel instigated its probe Dec. 2 but decided to extend the examination a maximum of 45 days before deciding a course of action by March 2.

Tiahrt, engaged in a campaign for the U.S. Senate against fellow GOP Rep. Jerry Moran, said he expected to be “fully exonerated.”

Tiahrt’s relationship with PMA and the firm’s clients first came under scrutiny by the Office of Congressional Ethics, an independent branch of the House created two years ago by the Democratic leadership to shine a light on allegations of unethical conduct. OCE recommended the regular House ethics committee delve more deeply into Tiahrt and Visclosky, but proposed dismissal of cases against five other members of the House defense appropriations subcommittee.

Tiahrt cooperated with OCE but requested in November that OCE turn his case over to the full House standards committee. OCE and the regular House panel have quarreled over jurisdictional issues and investigatory processes.

“I asked for this matter to be transferred to the standards committee because I respect their ability to professionally review my defense appropriations vetting process,” he said. “We have every confidence that as the committee examines the facts, it will not only confirm the integrity of our rigorous procedures, but will find our vetting standards to be a professional model for other offices to adopt.”

The investigations concern earmarks won by lawmakers for PMA and whether federal funding came in return for campaign contributions. The FBI raided PMA’s offices in 2008.

The Center for Responsive Politics produced a list indicating Tiahrt accepted $351,000 from PMA or the firm’s clients since 1998.

In terms of Tiahrt, investigators are interested in appropriations and earmark requests tied to Boeing, Aeroflex and Teledyne Technologies. All have a commercial presence in Wichita, and Boeing and Aeroflex employ thousands of people in Tiahrt’s congressional district.

While in the House, Tiahrt has emphasized the securing years of millions of dollars in defense aid for companies in the 4th District.

A spokesman for Moran’s campaign had no comment about developments in Tiahrt’s case.

Tiahrt and Moran are competing to succeed U.S. Sen. Sam Brownback, a Topeka Republican who is seeking the GOP nomination for governor.