OKLAHOMA CITY (AP) — A political maverick nicknamed "Dr. No" for his favorite vote, U.S. Sen. Tom Coburn was more than a bomb-thrower during his decade in the U.S. Senate — he also earned a reputation as a statesman willing to reach across the aisle to come up with solutions to the nation's budget woes.

The 65-year-old's announcement late Thursday that he is stepping down from his seat at the end of the year amid another battle with cancer signals the departure of a major political player in Washington, and the deep bench of Oklahoma Republicans looking to replace him undoubtedly will be influenced by his legacy.

"He's not a politician at all. He hates politics," said U.S. Rep. Tom Cole, a six-term Republican from Oklahoma who was Coburn's campaign consultant when Coburn first ran for the U.S. House during the Republican Revolution in 1994. "I think he's made it possible for people to propose bold solutions and survive, and other politicians recognize he's absolutely as incorruptible as any human being could be."

An obstetrician from Muskogee, Coburn wanted to be known as a true citizen-legislator, and he frequently clashed with colleagues on both sides of the aisle. But he also managed to elevate the dialogue on issues such as pork-barrel spending and government waste. Less than a year after his election to the Senate in 2004, Coburn drew the ire of some of his GOP colleagues when he offered an amendment to eliminate funding for the so-called "Bridge to Nowhere" in Alaska, a project that became symbolic of wasteful spending on pet projects by powerful politicians.

His office routinely produced reports on government waste and inefficiency, including his annual "Wastebook" that highlights dubious government spending and his 37-page report in 2011 dubbed "Subsidies of the Rich and Famous" that detailed nearly $30 billion spent annually on government tax breaks and federal grant programs for millionaires.

"He had a reputation as a maverick and an outsider, but Tom Coburn basically did what he thought was best for Oklahoma and the country," said Chad Alexander, former chairman of the Oklahoma Republican Party and now a GOP political consultant. "His legacy, I believe, will be the excessive government spending and the radical growth of government and his attempts to neutralize that and stop the bleeding."

Coburn's willingness to negotiate was evident when it came time for elected leaders to do the heavy lifting. He was a member of the National Commission on Fiscal Responsibility and Reform created by President Obama in 2010 to develop solutions to improve the nation's fiscal health. A year later, he was a member of the bipartisan "Gang of Six" senators who offered a major plan to cut the deficit by almost $4 trillion over the next decade.

And Coburn's ability to look past partisan divides was noted in statements released yesterday from colleagues including Senate Republican leader Mitch McConnell and President Barack Obama, who was a freshman U.S. senator with Coburn in 2004.

"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.

Coburn also wasn't afraid to speak his mind, either on the Senate floor or in town hall meetings across the state that occasionally grew raucous.

Describing his frustration with Congress in 2011, Coburn quipped at a town hall meeting in northeast Oklahoma: "It's a good thing I can't pack a gun on the Senate floor."

Coburn's office quickly issued an apology on the senator's behalf, but Coburn himself was dismissive of his critics.

"Political correctness is B.S.," Coburn told The Associated Press at the time. "Tell 'em to get over it."

He was equally blunt with critics on the right. When some constituents complained after a newspaper photograph showed him embracing Obama after the president's first speech to a joint session of the House and Senate, Coburn defended the relationship and said that while he and Obama disagree frequently on policy, the two "are very good friends."

Coburn was first treated for prostate cancer in 2011, and has battled numerous health issues.

He revealed in 2003 he'd been diagnosed with colon cancer and had undergone surgery and chemotherapy. Coburn also was treated for malignant melanoma in 1975, and had a benign tumor removed from his pituitary gland in 2007.

Coburn already had vowed not to seek re-election in 2016, but his resignation this year expedites a series of political moves in heavily conservative Oklahoma that could result in one or more open U.S. House seats and statewide offices.

Gov. Mary Fallin, who said Friday she won't run for Coburn's seat, will call for a special election, and the filing and election dates will coincide with those for the 2014 cycle. The timing is significant in Oklahoma because nearly all statewide officeholders and any member of the U.S. House who runs for the seat will have to vacate their current position to become a candidate.

"This will be one of the most significant political realignments we've had in a generation," said Alexander, the Republican strategist. "But one thing I can tell you: We're not going to find another Tom Coburn."