WASHINGTON (AP) — Democratic U.S. Rep. Raúl M. Grijalva of Arizona, who championed environmental protection during his 12 terms in Congress, died Thursday from complications from cancer treatments, his office said.

Grijalva, who was 77, had risen to chair the U.S. House Natural Resources Committee and was the top Democrat on the committee until earlier this year. He had been absent from Congress as he underwent cancer treatment in recent months.

Grijalva’s office said in a statement, “From permanently protecting the Grand Canyon for future generations to strengthening the Affordable Care Act, his proudest moments in Congress have always been guided by community voices.”

Another Democratic House member, Rep. Sylvester Turner of Texas, died last week from health issues.