Republican Senator James Inhofe, a Republican from Oklahoma, announced Monday he’ll retire from the Senate at the end of this year. 

The 87-year old Inhofe has served in the Senate since 1995 and won re-election overwhelmingly in 2020 in the red state, pledging to serve one final term. But he is opting to leave earlier to care for his ailing wife, according to a person familiar with the plans, who asked for anonymity to discuss them.

“It is bittersweet, but with a clear heart, that Kay and I announce that at the end of the year, I will retire from the United States Senate,” Inhofe wrote in a letter to Oklahoma’s secretary of state. “Throughout our years there has been one constant – making the world safer and better for our 20 kids and grandkids and the next generation of Oklahomans. It is now time for that next generation of Oklahomans to have the opportunity to serve the state in the U.S. Senate.”

Inhofe’s sudden announcement is set to spark a special election and likely a competitive primary among Oklahoma Republicans, given the overwhelming GOP tilt of the state. 

Inhofe is an Army veteran and former mayor of Tulsa who’s been active in GOP politics since the 1960s. On Capitol Hill, he’s perhaps best known as a leading critic of climate science and the idea that manmade causes are driving up global temperatures. 

On Monday afternoon, Inhofe’s colleague, Senator Jim Cramer, issued a statement about Inhofe’s resignation before the Oklahoma senator made the announcement.

“Senator Jim Inhofe is a giant in the Senate and I consider him a great mentor and close friend,” Cramer said. “He’s just one of those mentors who has ultimate integrity, intellectual curiosity, institutional knowledge, and at the end of the day is one of the greatest gentlemen of the United States Senate. The impact of Senator Inhofe’s public service cannot be overstated. He will be sorely missed in the Senate.”