President Obama offered a personal tribute to Sen. Tom CoburnThomas (Tom) Allen CoburnMr. President, let markets help save Medicare Pension insolvency crisis only grows as Congress sits on its hands Paul Ryan should realize that federal earmarks are the currency of cronyism MORE on Friday after the Oklahoma Republican announced that he would retire at the end of the year amid a battle with cancer.

"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 in a statement issued by the White House.

The president noted that he and Coburn entered the Senate at the same time and became friends after their wives struck up a conversation at an orientation dinner.

"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," Obama said.

"The people of Oklahoma have been well-served by this 'country doctor from Muskogee' over the past nine years, and I’m confident that Tom’s strength and optimism will carry him through the battles to come," he added. "Michelle and I will always be grateful to Tom and Carolyn for their friendship, and we wish them all the best in all the years ahead."

The friendship between Obama and Coburn has become a Washington legend, and last year the president wrote a profile on the lawmaker for Time magazine's Top 100 most influential issue. 

In that, he joked that both men held out hope for convincing the other of their political worldview.

"But in the mean time, we'll settle for being friends," Obama said.

In a statement Thursday night, Coburn said his decision to retire "isn't about my health, my prognosis or even my hopes and desires.

"As a citizen, I am now convinced that I can best serve my own children and grandchildren by shifting my focus elsewhere. In the meantime, I look forward to finishing this year strong," he said.