Longtime Michigan Congressman Bob Carr, who represented the state in the U.S. House of Representatives for 18 years, has died. He was 81 years old.

Carr, a Democrat, was first elected to Congress in 1974 and held his seat until 1980, when he lost re-election. He regained the seat two years later and held it until 1995.

His constituency changed due to redistricting, but his seat typically represented a portion of central Michigan.

Carr made a name for himself as a critic of the Vietnam War. During his first term in Congress, the 31-year-old sponsored a resolution calling on congressional Democrats to “strongly oppose the authorization of any further military aid to South Vietnam or Cambodia in fiscal year 1975.”

Carr has introduced more than 2,000 bills during his time in Congress, but he has also been sharply critical of the body. “On Capitol Hill, we don’t do much critical thinking,” Carr said in a 2017 discussion hosted by the National Archives and the U.S. Association of Former Members of Congress. “It’s all about hedging, postponing problems and getting credit.”

Carr said his membership on the House Armed Services Committee increased his respect for the country’s military. “I think the military is critically thinking to an appropriate degree. I think they look at the threats more holistically. … Their incentives are not re-election next week. Their incentives are, I think, really in the right place,” he said in the 2017 discussion.

Members of Michigan’s congressional delegation and those running for membership praised Carr on Tuesday.

Curtis Hertel, a Democrat running for Michigan’s 7th Congressional District, said Carr served central Michigan “with grace and determination.”

“Congressman Carr was a force for peace abroad, advocated for de-escalation of the Vietnam War and was a leader in the SALT II arms control negotiations during the Cold War,” Hertel said. “As a longtime member of the Appropriations Committee, Congressman Carr modernized our transportation system. … He helped connect our country.”

Democratic Rep. Elissa Slotkin, who currently holds the seat Hertel is seeking and is now running for the U.S. Senate, said Carr “leaves a legacy of dedicated service to the people of Michigan.”

“He brought principle and passion to his time in Congress and, after his career as an elected official, spent countless hours helping new members better serve their constituents,” Slotkin said.

Carr was diagnosed with multiple myeloma, a type of blood cancer, in 2006. He was committed to advancing cancer research and treatment.