The race is on to replace Sen. Tom Coburn (R-OK), who recently shocked the political world by announcing he’ll leave Congress after 2014 — two years before his term is up. The Oklahoman, a staunch conservative and unwavering fiscal hawk, has been a thorn in the side of both Republicans and Democrats, with his pioneering brand of obstructionism earning him the moniker “Dr. No.”

Replacing Coburn with an equally colorful or caustic personality would be a tall order, for he is truly one of a kind. Here are some highlights from his 15-year career in Congress (nine years in the Senate and, before that, six years in the House).

— In 1997, Coburn was the subject of an amusing headline: “GOP Lawmaker Blasts NBC For Airing ‘Schindler’s List.'” As the Chicago Tribune reported at the time, the then-congressman fumed that the network had sunk “to an all-time low, with full-frontal nudity, violence and profanity” by airing the graphic and emotional film about the Holocaust during a family hour. He declared that parents and “decent-minded individuals everywhere” should be outraged.

— In 2004, while running for Senate, Dr. Coburn, as the physician still prefers to be called, said he supported the death penalty for “abortionists and other people who take life,” according to the Washington Post. His campaign tried to soften his inflammatory comments but didn’t disavow them. As it turns out, they didn’t really hurt him in the socially conservative state of Oklahoma, and he easily won the election.

— In July 2009, Coburn told Sonia Sotomayor, who would soon become the first ever Hispanic Supreme Court justice, that “you have lots of ‘splainin to do.”

— In October 2009, Coburn compared federal funding of political science research to waterboarding his grandchildren. “We’re going to waterboard them,” he said on the Senate floor. “We’re going to flood them with debt.”

— In October 2009, Coburn sought to turn the gay community against the emerging health care reform law. In an online op-ed for the LGBT magazine The Advocate, he cited the rationing of AIDS treatment by the government as an example of why a public insurance option would be a bad idea. “These bureaucratic inefficiencies and mismanagement have literally cost lives,” wrote Coburn and co-writer Christopher Barron, the founder of GOProud, a group that represents gay conservatives.

— In March 2010, as part of his relentless efforts to prevent passage of Obamacare, he proposed a series of politically-charged amendments, one of which prohibited child molesters, rapists and sex offenders from obtaining Viagra through the insurance exchanges. It was called the “No Erectile Dysfunction Drugs To Sex Offenders” amendment, and also prevented coverage for abortion drugs. Democrats rejected it, and Sen. Max Baucus (D-MT) accused Coburn of making “a mockery of the Senate.”

— In January 2013, Coburn mused that it might be a “wonderful experiment” to breach the debt ceiling, risking the first-ever default on the country’s obligations, because it means the U.S. would “not have to borrow against the future of our children.” Economists say a default on the national debt could spur a global economic meltdown, and leaders of both parties insist it must never happen.

— In October 2013, Coburn called Senate Majority Leader Harry Reid an “absolute asshole” at a fundraiser in New York City. He later walked it back — sort of. “My words weren’t appropriate,” he said, “but my frustrations are real.”