WASHINGTON - Wyoming Sen. Craig Thomas' chief of staff is leaving to take a job as president and chief executive officer for an organization that aims to increase the role of private companies in the public sector.

In his new job Chris Jahn will be a major participant in a contentious debate over which federal jobs can and should be performed by private companies.

Jahn's last day as chief of staff for the Republican senator will be March 19. He will assume the top position at Contract Services Administration of America on March 22.

Thomas' current legislative director, Shawn Whitman, will be promoted to chief of staff and Bryn Stewart, who currently handles tax issues for Thomas, will be promoted to legislative director.

The 34-year-old Jahn began working for Thomas in 1994, the lawmaker's last year in the House of Representatives. Thomas served in the House from 1990 to 1994, when he was elected to the Senate.

Over the years Jahn, a Casper native, has progressed from being a legislative assistant to legislative director in 1999 to chief of staff in 2001. Jahn is a graduate of Kelly Walsh High School and New York City's Columbia University. Jahn, who was an intern in Thomas' office in 1992, and his college roommate formed a business buying and selling books after they graduated. Jahn sold his share of the business to the roommate when he joined Thomas' staff.

Jahn, who is married and has a 6-year-old daughter and one-and-a-half-year-old son, has mixed feelings about leaving Thomas' office.

"This has been my dream job and I am reluctant to go," Jahn said. "Craig is really easy to work for. He sets a clear strategic direction and leaves it up to you to implement it. He trust and relies upon you to do the dirty work."

Jahn cited Thomas' current effort to overhaul the program for cleaning up abandoned mines as an example of Thomas' style. He said Thomas has made it clear that he wants a plan that both gets Wyoming the more than $400 million in back payments that it is owed and guarantees future payments to Wyoming, but has left the details to the staff.

Under Senate rules Jahn will be unable to lobby Thomas or any of the senator's staff members for the next year. He will be able to lobby other senators and their aides.

Jahn said that the restriction would not be a problem because he does not expect to be doing too much lobbying. His focus will be more on running the organization.

On its Web site, (www.csa-dc.org/) the Contract Services Association of America describes itself as "the premier organization representing the Government Services Contracting Industry in Washington, D.C."

The Arlington, Va., organization's members include everyone from relatively small construction firms to the large defense contractor Northrop Grumman Corporation. The organization promotes "competitive outsourcing," in which private companies bid to do jobs that are currently performed by federal workers. Bush administration officials say it will improve the efficiency of the federal government, while labor union officials say it is an effort to weaken their power.

"It's a hot issue, so that will be challenging," Jahn said.