By Avery Palmer, CQ Staff

Conflicts over federal land, water and other natural resources are at the heart of politics in the modern West, from which the next secretary is likely to come. Beyond overseeing the National Park Service, he or she will direct the Fish and Wildlife Service, which manages the national wildlife refuge system; the U.S. Geological Survey and Minerals Management Service, which regulate energy, mineral and biologic resources; the Bureau of Land Management, which directs protection of, and resource extraction from, federal property; the Bureau of Reclamation, the nation’s largest wholesale water supplier and second-largest hydroelectric power producer; and the tribal social services of the Bureau of Indian Affairs.

For McCain

Wayne Allard , Colorado senator

He’s retiring this fall to honor a promise to serve only two terms, he says, though he would have otherwise faced an intense re-election battle. But he turns 65 in December and so he has time for a new Washington chapter in his life. One of the least flashy senators, he’s a states-rights-loving conservative with an innate skepticism of the federal government. Allard has angered environmentalists for backing conservative proposals for limiting the reach of federal endangered species protections. He is a strong advocate for an oil shale leasing program in the Rocky Mountains, which environmentalists oppose on the grounds that the technology is not sufficiently developed. But he also has backed environmental protection for lands and resources in his state, including the recent creation of Great Sand Dunes National Park.

Steve Pearce ,New Mexico congressman

Having represented his state’s sprawling and rural southern half for six years, he’s now trailing Democratic Rep. Tom Udall in the race for the Senate seat from which Republican Pete V. Domenici is retiring. If he loses a month from now, a Cabinet job could be a more than adequate consolation. The former owner of an oil well services company, Pearce is a vocal member of the House Natural Resources Committee, who tends to favor expanded energy development on federal lands. A McCain administration could count on him to support additional oil and gas leasing, timber harvesting and mining. But his staunch conservatism could bring intense opposition from environmentalists.

Dirk Kempthorne , current secretary

Perhaps the simplest option for McCain would be to retain his former senatorial colleague. The two were in the Senate together from 1993 through 1998, when Kempthorne was elected governor of Idaho; he resigned in May 2006 to become the Bush’s administration’s second Interior chief. Kempthorne has since been no stranger to controversy. He has proposed regulatory changes that environmentalists say would roll back the endangered species program and created a stir by proposing to allow loaded guns in national parks. But staying in office longer than 20 months could allow him to advance one of his signature issues: A plan to provide billions in extra funding to the National Park Service in the coming decade.

For Obama

Brian Schweitzer , Montana governor

He has experience in public land and natural resources policy that could make him a prime candidate. A former agronomist and businessman, he became a Democratic hero when he won the governorship of such a conservative state in 2004. Obama now has an outside chance of carrying Montana, even after crossing Schweitzer off his long list of vice presidential options. And the governor received rave reviews for his speech at the Democratic National Convention this summer in support of alternative energy sources. In fact, energy is one of his strong interests that could carry over into a role as steward of the nation’s public lands. He is also a firm supporter of gun rights, which could help secure the trust of the outdoorsmen who use federal lands and generally distrust Washington.

Jay Inslee , Washington congressman

During six terms representing suburban Seattle, he has become one of the leading liberal voices in the House on energy and natural resources issues. He is a strong advocate for environmental protections on public lands and has opposed controversial proposals to allow more logging in national forests. So for environmental groups he would be an attractive pick. Advancing renewable sources of energy is a top priority of his, and Inslee would mark a clear reversal from Bush administration priorities to aggressively expand oil and gas development, and mining. But he would be a controversial choice who could alienate conservatives and Western energy producers.