By STEPHEN GROVES and LEAH ASKARINAM, Associated Press

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

Grijalva, the son of a Mexican immigrant, was first elected to the House in 2002. Known as a liberal leader, he led the Congressional Progressive Caucus in 2008 and dedicated much of his career to working on environmental causes on the Natural Resources Committee. He stepped down from that position this year, after announcing that he planned to retire rather than run for reelection in 2026.

Grijalva had announced in April last year that he had been diagnosed with cancer, but would be able to continue his work. Despite missing hundreds of House votes, he sought reelection and won easily in one of the most solidly Democratic districts in Arizona.

The seat will remain vacant until a replacement is selected in a special election later this year.

The Democratic primary is likely to be a fierce battle between allies of Grijalva, a longtime Southern Arizona power broker who led an influential bloc of progressive elected officials, and a more moderate faction. Possible contenders include his daughter, Adelita Grijalva, a member of the Pima County Board of Supervisors, and Tucson Major Regina Romero, one of Grijalva’s longtime allies.

Democratic Sen. Ruben Gallego of Arizona, who served in the House until last year, said in a statement that “Congressman Grijalva was not just my colleague, but my friend.”

“As another Latino working in public service, I can say from experience that he served as a role model to many young people across the Grand Canyon State. He spent his life as a voice for equality,” Gallego added.

Grijalva started out as a community organizer in Tucson and served on the local school board for years before being elected the Pima County Board of Supervisors. He resigned from that post in 2002 to seek office in what was then Arizona’s newly created 7th Congressional District.

Grijalva prided himself on representing what he considered the underdogs, those without a voice.

A member of the House Natural Resources Committee for more than two decades, he worked on issues that ranged from securing water supplies for drought-stricken parts of Arizona and the West to securing funding for the federal Land and Water Conservation Fund, which safeguards natural areas and provides recreation opportunities to the public.

He also played a key role in writing the National Landscape Conservation System Act and the Federal Lands Restoration Act, which were passed and signed by President Barack Obama.

In recent years, he also led advocacy in Congress for the creation of a new national monument near the Grand Canyon. It was part of an effort to protect the area from uranium mining and to acknowledge repeated calls by Native American tribes that sought to protect more of their ancestral homelands.

He also opposed plans to develop a major copper mine in southern Arizona.

Rep. David Schweikert, a Republican and fellow Arizonan, said on the social platform X that Grijalva “was always very kind to me — he had a great sense of humor. As a fellow animal lover, we often found ourselves working together on animal protection issues.”