President Obama lamented Friday the retirement at the end of the year of Sen. Tom Coburn, R-Okla., an ideological foe but rare GOP friend of the president on Capitol Hill.

“Those of us who have had the privilege of serving with Tom Coburn will be sad to lose him as a colleague here in Washington,” Obama said.

“Even though we haven’t always agreed politically, we’ve found ways to work together — to make government more transparent, cut down on earmarks and fight to reduce wasteful spending and make our tax system fairer,” the president added.

Coburn announced late Thursday that he would leave Congress at the end of the current session. The conservative lawmaker is battling a recurring case of prostate cancer but said his decision to retire was not related to health concerns.

"This decision isn’t about my health, my prognosis or even my hopes and desires," Coburn said. "Our founders saw public service and politics as a calling rather than a career. That’s how I saw it when I first ran for office in 1994, and that’s how I still see it today.”

Obama noted that he and Coburn became friends after their wives met at a Senate orientation dinner. The president has repeatedly gone out of his way to praise Coburn for working across the aisle, even while slamming the Republican Party as a band of obstructionists.

And the president predicted that Coburn was well equipped to handle his health struggles.

“The people of Oklahoma have been well-served by this ‘country doctor from Muskogee’ over the past nine years,” Obama said, “and I’m confident that Tom’s strength and optimism will carry him through the battles to come.”