A top opponent of wasteful government spending is stepping down from the U.S. Senate.
Sen. Tom Coburn, R-Okla., is resigning at the end of this year with two years still left in his term.
The 65-year-old lawmaker has been told his prostate cancer has returned, but he says his health isn't the reason for retiring.
"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," Coburn said in a statement.
Known as a conservative maverick in Congress, Coburn published a yearly book on wasteful spending, drawing attention to some of the most outrageous examples.
In a 2011 report called "Subsidies of the Rich and Famous," he pointed out $30 billion spent annually on tax breaks and federal grant programs for millionaires.
Senate Minority Leader Mitch McConnell, R-Ky., released a statement Thursday describing Coburn as "one of the most intelligent, principled and decent men in modern Senate history."
"When it comes to the transcendent debate over the size and cost of government, Tom Coburn is simply without peer," McConnell said. "No one has done more to awaken Americans to the threat posed by a government that chronically spends more than it takes in, and no one has worked harder at finding a solution."
Among his numerous findings of government waste, late last year Coburn was among a group of senators who released the findings of a two-year probe into alleged abuses in how Social Security disability benefits were approved at one federal office.
That study detailed inappropriate conduct between Social Security law judges, a law firm, and doctors in approving benefits, and an apparent lack of oversight from the agency.