CHEYENNE - Wyoming's senior U.S. senator is on the list of candidates to replace outgoing Interior Secretary Gale Norton, the Casper Star-Tribune learned Tuesday.

Craig Thomas, who announced earlier he would seek re-election to the U.S. Senate this year, was a candidate for the Cabinet post when Norton won the appointment five years ago.

Thomas, 73, could not be reached for comment Tuesday evening. But a source close to Thomas who spoke on condition of anonymity said the Republican had talked with the White House about the job and was on the "operable list" of candidates to replace Norton.

Thomas's spokesman, Cameron Hardy, declined Tuesday to answer any specific questions about the possibility of the senator being in the running for the position.

"He's definitely happy he's doing the job he was elected to do and (to) continue to serve the people of Wyoming," Hardy said.

Vice President Dick Cheney suggested Thomas as a candidate for Interior secretary the last time the position was open, but Norton ended up being chosen to fill the slot, Hardy said.

A former state legislator from Casper, Thomas was elected to the U.S. House in a special election in 1989 to replace Cheney when he was appointed secretary of defense. Thomas was elected to the U.S. Senate in 1994 and to a second term in 2000.

Norton, a former Colorado attorney general, announced Friday she will leave the office at the end of March. She spearheaded the administration's efforts to open more federal land in the West to oil and gas development.

The White House has said Bush will nominate another Westerner with pro-development views to replace her.

Idaho Gov. Dirk Kempthorne, a Republican, is considered a favorite candidate to replace Norton, according to the Denver Post. A former U.S. senator, he is conservative on land and environmental issues.

Thomas is considered a fiscal conservative.

Hoping to put another Coloradoan in charge of the nation's public land and resources, Republican Sen. Wayne Allard asked the White House Tuesday to nominate former Sen. Ben Nighthorse Campbell to succeed Norton, The Associated Press reported. Campbell retired from Congress in 2005 after two terms in the Senate and three in the House.

As the job requires Senate confirmation, Thomas, as a member of that body, could have an edge. He sits on the Senate Energy and Natural Resources Committee, and as chairman of the National Parks Subcommittee he presided over a hearing Tuesday about President Bush's requested National Park Service budget for fiscal year 2007.

Other names being circulated as potential candidates include Colorado Gov. Bill Owens, retiring Rep. Joel Helley of Colorado and former Montana Gov. Mark Racicot.

Whoever gets the job will have a plateful of issues.

The Bush administration wants to open the Arctic National Wildlife Refuge and off-shore gas and oil fields for drilling, and the Interior Department is wedged in a bitter legal battle over royalties due to American Indians.

Star-Tribune Washington reporter Noelle Straub contributed to this report.