WASHINGTON — As the lobbying controversy continues to loom large in Washington, Sen. Max Baucus and Rep. Dennis Rehberg have both recently removed the lobbyists who served as treasurers of their fundraising campaign committees to avoid any appearance of impropriety.

Although Sen. Conrad Burns did not have a lobbyist as treasurer of his committees, his campaign chairman, Mark Baker, works as a registered lobbyist. Burns has no plans to replace him, a spokesman said.

Eric Iverson, Rehberg’s chief of staff, said the decision was made a month to six weeks ago to replace the treasurer of his leadership political action committee with a non-lobbyist. Rehberg wanted both to put in place a treasurer able to handle an increase in the committee’s activity and to avoid any possible unseemly appearances.

“We just wanted to avoid any sort of appearance of impropriety,’’ Iverson said. “We didn’t want this PAC issue to become a distraction. It ends up taking the attention away from important issues Denny is working on.’’

Rehberg also wanted to hire a firm that specializes in leadership political action committees, which lawmakers can use to give money to other candidates.

“Denny wants to get quite a bit more actively involved in helping out Republican candidates running at the federal level,’’ he said. “We wanted to get a PAC treasurer who specializes more in reporting and dealing with PACs that are more active.’’

The treasurer of Rehberg’s committee, Building Our Opportunities Together or Boot PAC, had been Republican fundraiser and lobbyist Mark Valente III.

Valente has two lobbying firms in Washington, Valente & Associates and MV3 & Associates. According to a study by The Center for Public Integrity, Valente has served at the helm of 15 PACs since 1998, including the leadership PACs of at least nine Republicans in Congress.

Valente’s clients include North American Coal Corp, International Brotherhood of Teamsters and Berwind Development Services.

Iverson said Valente served until Jan. 31, the date when the 2005 year-end reports were due. Rehberg has since hired Political Compliance Services, an accounting services company based in northern Virginia near Washington, D.C., that specializes in Federal Election Commission regulations.

The company produces and files financial disclosure reports for candidates and parties. Iverson said one of the company’s employees would likely be listed as treasurer.

Baucus spokesman Barrett Kaiser said the senator has decided to replace his treasurer and also to voluntarily tighten restrictions on his staff’s involvement with lobbyists.

“In light of recent events, Max asked the office to do a top to bottom review of our procedures,’’ Kaiser said. “Out of an abundance of caution, he’s made two immediate changes. The first one is that all of his offices and staff will immediately abide by lobbying reform legislation proposed by Max and (Senate Minority Leader) Harry Reid and ban all gifts, meals and travel by lobbyists.’’

Kaiser said Baucus also has replaced William Oldaker, who had served as treasurer of his Glacier leadership PAC and as assistant treasurer of his re-election committee, Friends of Max Baucus. The positions are now open and Baucus is looking for a replacement.

Kaiser noted that Oldaker is an expert on campaign finance law and a former counsel to the FEC.

According to a study by The Center for Public Integrity, Oldaker has served as the treasurer of 23 political committees since 1998, including the leadership PACs of Reid and Sen. Edward Kennedy, D-Mass. Roll Call newspaper reported that both Reid and Kennedy have recently cut ties with Oldaker.

Since 1998, Oldaker has been a principal lobbyist at The National Group; Oldaker, Biden & Belair; and Oldaker & Harris. His clients largely consist of colleges, universities and hospitals.

Burns currently has a lobbyist, Mark Baker, as the overall chairman of his re-election effort. Burns campaign spokesman Jason Klindt said the senator has no intention of replacing him.

“Mark Baker is a good friend and trusted adviser of the senator,’’ Klindt said. “He and the senator have traveled the state and they both understand the diverse nature of the state and its people. Mark’s family is just one of the many Montana families the senator is fighting on behalf of.’’

Sens. Joe Lieberman, D-Conn., and Barack Obama, D-Ill., last week called for Congress to outlaw the practice of having lobbyists as treasurers.

Obama said the practice “raises great suspicion’’ because of the “appearance of potential influence.’’