Tom Coburn was born in Casper, Wyo., and now lives in Muskogee, Okla. He earned a bachelor's in accounting from Oklahoma State University.
He was manufacturing manager for the Ophthalmic Division of Coburn Opticals in Virginia from 1970 to 1978.
He later earned a medical degree from the University of Oklahoma and has maintained a medical practice in Muskogee since 1988, specializing in family medicine and obstetrics.
Coburn was elected to the U.S. House in 1994 and did not seek re-election in 2000, keeping a term-limit pledge he made to voters.
He was elected to the U.S. Senate in 2004.
He and his wife, Carolyn, have three children.
Tom Coburn was known as a conservative maverick during his three terms in Congress representing Oklahoma's 2nd District, and he has continued that role in the Senate.
He has been most vocal in opposing the earmarking of special projects, and he is among the few members of Congress who do not seek such projects for their state.
"I've got a flat forehead from beating my head against the wall," Coburn told voters during a town hall meeting in July 2010.
He has been a fierce critic of the growth of the federal deficit and the size of government, releasing a series of oversight reports that detailed what he said was wasteful government spending.
A 37-page report in 2011, dubbed "Subsidies of the Rich and Famous" detailed nearly $30 billion spent annually in government subsidies, tax breaks and federal grant programs to millionaires.
He sponsored the Earmark Transparency Act in 2010, legislation that would create an online database for the public to obtain detailed data on earmark spending.
Coburn drew some constituent complaints after a newspaper photograph showed the senator hugging President Barack Obama after the president's first speech to a joint session of the House and Senate.
He said he and the president "are very good friends," though they do not share the same political philosophy. Coburn said he and Obama hit it off during orientation as freshmen senators in 2004.
Coburn's thwarting of legislation considered worthy by Democrats has frustrated Senate Majority Leader Harry Reid. "You cannot negotiate with Coburn," Reid declared in 2008. "It's just something you learn over the years is a waste of time."
Coburn's ideological bent on spending did not keep him from voting for the 2008 financial bailout bill, which was opposed by some conservatives.
Some angry constituents at a town hall meeting in Oklahoma City questioned his vote for the measure, but the senator stood his ground. Without the bailout, Coburn said, the nation's economy could shrink to its level in 1990. "How many of you think you'd still have a job?" he asked.
He said he did not like the legislation but voted for it in effort to prevent a repeat of the Great Depression, which he said was caused by the failure of the nation's leaders to act after the 1929 stock market crash.
Coburn is an obstetrician and has continued to deliver babies for free, despite the threat of censure for violating conflict-of-interest rules of the Senate. He said he welcomed debate on the issue on the Senate floor.
He kept his pledge to leave Congress after three terms and returned full time to his medical practice in Muskogee, Okla. As a doctor, he has delivered more than 4,000 babies.
Coburn has had several health scares, including surgery for prostate cancer that was discovered at an early stage in 2011. His spokesman said at the time that Coburn was expected to make a full recovery. He underwent surgery and chemotherapy for colon cancer in 2003 and had a benign tumor removed from his pituitary gland in 2007.
He ignored pressure from the Republican establishment when he decided to run for the GOP Senate nomination in 2004. U.S. Sen. Jim Inhofe and other prominent GOP officials were backing former Oklahoma City Mayor Kirk Humphreys, who was the early favorite but finished second to Coburn.
Coburn pledged to serve no more than two terms in the Senate if he won.
Despite a four-way race against a Democrat and two independents in the November 2010 general election, Coburn had the widest margin of victory among statewide candidates with more than 70 percent of the vote.
Committee Assignments: Homeland Security and Governmental Affairs; Judiciary; Finance
American Conservative Union Rating: 100
Americans for Democratic Action Rating: 5
Tom Coburn will finish out the current congressional session and then resign from his seat in January 2015, nearly two years before his term is scheduled to end.
(Last updated by The Associated Press on June 24, 2014.)