A major environmental group is launching a bilingual television and digital ad campaign targeting Sen. Dean Heller over his support for embattled Environmental Protection Agency head Scott Pruitt.

The League of Conservation Voters, a 501(c)(4) nonprofit, is leading several environmental groups including the Nevada Conservation League in funding a $257,000 ad campaign on Thursday urging Heller and Colorado Republican Sen. Cory Gardner to hold Pruitt “accountable” and sign a resolution asking the former Oklahoma attorney general to resign.

The ad, entitled “Lot to Say,” claims Heller is “strangely silent” on various scandals facing Pruitt, including at least 12 investigations launched against Pruitt’s conduct by various federal oversight agencies including the EPA’s Inspector General, the House Oversight Committee, the General Accountability Office and the White House.

The ad in particular highlights a $43,000 soundproof phone booth that Pruitt installed in his office last year — which the GAO said last week violated federal spending laws. Heller, who voted to confirm the EPA chief last February, has not commented on any of the investigations targeting Pruitt.

“Dean Heller is letting industry polluters run the EPA and profit off of threatening Nevadans’ health,” Nevada Conservation League Director Andy Maggi said in a statement. “By failing to call for Scott Pruitt’s resignation, Heller is yet again showing that he is bought and paid for by corporate special interests and has no interest in representing Nevadans by standing up to the Trump administration’s toxic agenda.”

Democratic Sen. Catherine Cortez Masto and Democratic Reps. Dina Titus and Ruben Kihuen all signed onto a resolution earlier in April calling on Pruitt to resign.