One of the most aggressive Republican budget hawks in the U.S. Senate has decided to end his legislative career early, as Sen. Tom Coburn (R-OK) says he will leave the U.S. Senate at the end of this year's Congressional session.

While Coburn said his decision had nothing to do with his health, the Oklahoma Republican was recently diagnosed again with prostate cancer.

"Serving as Oklahoma’s senator has been, and continues to be, one of the great privileges and blessings of my life," Coburn said in a written statement issued Thursday night by his Senate office.

"But, after much prayer and consideration, I have decided that I will leave my Senate seat at the end of this Congress," said the GOP lawmaker who focused most of his legislative efforts on cutting spending.

A few hours before his announcement, Coburn sounded an almost wistful note on the Senate floor about his constant battles to rein in the size of the federal government, an effort that was never fully embraced by lawmakers in either party.

"In my nine years here, I have failed in my ability to convince my colleagues that we ought to be worried about this problem," the Oklahoma Republican said.

After arriving in the Senate following the 2004 elections, Coburn took over the floor role that had been filled for many years by Sen. John McCain (R-AZ), as Coburn tried to publicly shame members of both parties into cutting down on government waste and spending.

But just like McCain, Coburn's efforts were not warmly embraced by many members of his own party, who resisted his budget cutting amendments on the Senate floor, no matter how much money they might save the taxpayers.

Until deficit reduction became politically "cool" around 2010, Coburn often had a difficult time rounding up 25 votes on the GOP side for any plan to cut spending, as the obstetrician sometimes resorted to arcane parliamentary tactics to make his point.

In 2010, Coburn tried to use a procedural tactic on the Senate floor known as a "clay pigeon" to break one piece of a budget bill into 17 separate parts, which would have stalled action on the plan.

"He's the kind of guy the founders had in mind when the Senate was created," said Sen. Jeff Flake (R-AZ).

"We may not always agree, but he's a good man and a good senator," said Sen. Chris Coons (D-DE), who added that he was praying for Coburn's health.

Senate GOP Leader Mitch McConnell called Coburn "a lasting credit to his beloved Oklahoma," labeling him "one of the most intelligent, principled and decent men in modern Senate history."

Coburn's decision means that his seat will come open at some point in 2015; a special election would be held to fill that remaining time.

Oklahoma is considered the reddest state in the nation, which would mean Republicans are the clear favorite to maintain his seat.

In 2016, Oklahoma voters would then elect someone to fill the seat for a regular six year Senate term.

Coburn was first elected to the U.S. House in the 1994 Republican Revolution. He limited himself to three terms (six years) in office, and went back to Oklahoma.

But when Sen. Don Nickles (R-OK) decided not to run for re-election, Coburn stepped in and won the seat.

Here is the statement issued by Coburn on Thursday night:

"Carolyn and I have been touched by the encouragement we've received from people across the state regarding my latest battle against cancer. But this decision isn't about my health, my prognosis or even my hopes and desires. My commitment to the people of Oklahoma has always been that I would serve no more than two terms. 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. I believe it's important to live under the laws I helped write, and even those I fought hard to block.

"As a citizen legislator, I am first and foremost a citizen who cares deeply about the kind of country we leave our children and grandchildren. As I have traveled across Oklahoma and our nation these past nine years, I have yet to meet a parent or grandparent who wouldn't do anything within their power to secure the future for the next generation. That's why I initially ran for office in 1994 and re-entered politics in 2004. I'm encouraged there are thousands of Americans with real-world experience and good judgment who feel just like I do. As dysfunctional as Washington is these days, change is still possible when 'We the People' get engaged, run for office themselves or make their voices heard. After all, how else could a country doctor from Muskogee with no political experience make it to Washington?

"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. I intend to continue our fight for Oklahoma, and will do everything in my power to force the Senate to re-embrace its heritage of debate, deliberation and consensus as we face our many challenges ahead.

"My God bless you, our state and our country."

One of the most aggressive Republican budget hawks in the U.S. Senate has decided to end his legislative career early, as Sen. Tom Coburn (R-OK) says he will leave the U.S. Senate at the end of this year's Congressional session. While Coburn said his decision had nothing to do with ...