A senior aide to Vice President Cheney is the leading contender to become a top official at the Energy Department, according to several current and former administration officials, a promotion that would put one of the administration's most ardent opponents of environmental regulation in charge of forming department policies on climate change.

F. Chase Hutto III has played a prominent behind-the-scenes role in shaping the administration's environmental policies for several years, the officials said, helping to rewrite rules affecting the air that Americans breathe and the waters that oil tankers traverse. In every instance, according to both his allies and opponents, he has challenged proposals that would place additional regulations on industry.

The move to elevate the domestic policy adviser to the post of assistant secretary for policy and international affairs signals the administration's determination to resist new environmental protections, environmentalists said.

The assistant secretary is the "primary advisor to the Secretary and the Department on energy and technology policy development," conducts overseas negotiations on energy issues such as climate change, performs environmental analyses, and "leads the Department's international energy initiatives," according to the agency's Web site.

Hutto did not respond to several requests for an interview. Cheney spokeswoman Lea Anne McBride would not comment on the matter, saying the office does not discuss pending nominations, but she confirmed that Hutto has helped shape administration policies on an array of issues, including proposed protections for endangered right whales and whether to regulate carbon dioxide emissions under the Clean Air Act.