A U.S. congressional leader on Wednesday issued a subpoena seeking information from climate activists over antitrust issues, joining other Republicans who have criticized companies’ growing concern for environmental, social and governance (ESG) matters.

Jim Jordan, chair of the House Judiciary Committee, wrote in a letter to a lawyer for Boston-based sustainability nonprofit Ceres that it “appears to facilitate collusion” in potential violation of antitrust law through its work with the Climate Action 100+. Ceres is a sponsor of the latter, an investor coalition aiming to convince companies to address climate change by cutting emissions or disclosing transition details.

The letter included a subpoena and states Ceres did not adequately respond to a previous information request.

Various Republican state officials have also demanded documents from top asset managers and cited possible violations of antitrust laws through their work with the coalition, though they have not brought charges. Top asset managers have defended their involvement, saying they still prioritize their fiduciary duty to clients.

Ceres General Counsel Mike Boudett said it intends to comply with the subpoena, and that redactions in previous material it turned over to Jordan’s committee were to comply with European privacy rules.

He said membership in the coalition did not pose antitrust issues since investors chose whether to join and use the group to engage with stock issuers.

“Nobody’s colluding with anybody. It’s like you and your friend deciding you want to get a burger so you go to a burger place,” he said.