March 28 (UPI) — Former Sen. Tom Coburn, known as “Dr. No” for his conservative stand on fiscal matters, died Saturday in Oklahoma, his family announced. He was 72.

His former aide,. Roland Foster, said he died from complications from prostate cancer, a disease that prompted his retirement from Congress in 2015.

“He’s been fighting up to the very end,” a family friend told The Oklahoman. “He was fighting for all of the things he still believed in.”

Coburn’s family said they’ll plan a memorial for him at a future date.

“Because of his strong faith, he rested in the hope found in John chapter 11 verse 25 where Jesus said, ‘I am the resurrection and the life. The one who believes in me, will live, even though they die.’ Today he lives in heaven,” the family said in a statement.

Coburn, an obstetrician who served three terms in the U.S. House and most of two terms in the Senate, campaigned on the promise not serve any more than three terms in each chamber. He was known for unwavering opposition to abortion, same-sex marriage, and federal government waste and expansion. He also didn’t believe in science-based global warming.

Despite their political opposition, Coburn was close friends with former President Barack Obama, who entered the senate at the same time in 2005.

“Tom and I entered the Senate at the same time, becoming friends after our wives struck up a conversation at an orientation dinner. And 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 of Coburn at his retirement in 2014. “The people of Oklahoma have been well-served by this ‘country doctor from Muskogee’ over the past nine years.”