Former Republican Sen. Pete Domenici, noted for his leadership on nuclear energy, died Wednesday at the age of 85.

The New Mexico Republican had been a key figure as chairman of both the Senate Budget and Energy and Natural Resources committees before retiring from the Senate in 2009 after six consecutive terms in Congress beginning in 1973.

Part of the reason he decided to retire was health related after doctors found that he suffered from a degenerative brain disease, according to the Albuquerque Journal. Domenici had been recovering from a recent abdominal surgery when he died on the same day as the opening of the Domenici Public Policy Conference, featuring former administration officials and lawmakers.

Domenici had been a senior fellow at the Washington-based think tank Bipartisan Policy Center, where he focused on energy issues.

He "was part of BPC's family from our early days, and much of our aspiration and approach is drawn from his insights and the example he set in public service," said Jason Grumet, president of Bipartisan Policy Center.

"Sen. Domenici was a true giant of the Senate," Grumet recalled, saying he was "best known for his leadership on both budget policy and energy policy." The senator served as chairman of the Senate Budget Committee from 1981 to 1987 and again from 1995 to 2001. He served as chairman on the Energy and Natural Resources Committee from 2003-2007.

"In 2005 and 2007, Senator Domenici led bipartisan efforts to adopt major energy legislation that helped usher in an era of American energy diversity and abundance, most notably the landmark 2005 Energy Policy Act," Grumet noted.

Domenici was tapped as a member of former President Barack Obama's Blue Ribbon Commission to find a solution to the nation's nuclear waste problems. The commission was established after the Obama administration withdrew its license to construct the Yucca Mountain waste facility, causing a heated discussion in Washington on the way forward for nuclear waste that resulted in litigation that reversed the decision.