Rep. Raúl M. Grijalva, D-Ariz., died Thursday due to “complications of his cancer treatment,” his office announced in a statement.

Grijalva, who served in the House for more than 20 years, was first elected to Congress in 2002. During that time he served as chair of the House Natural Resources Committee, co-chair of the Congressional Progressive Caucus and, most recently, as the top Democrat on the House Natural Resources Committee.

“He was steadfast in his commitment to produce lasting change through environmental policies — as he would say, ‘it’s for the babies.’ He led the Natural Resources Committee without fear of repercussion, but with an urgency of the consequences of inaction,” his staff said in a statement.

Grijalva began his career in public service as a community organizer in Tucson, Ariz. He chaired the Tucson Unified School District Governing Board for six years before serving on the Pima County Board of Supervisors for more than a decade.