The Republican chairman of the House science committee is threatening to subpoena a group of Democratic state attorneys general for all information related to their climate change investigations into Exxon Mobil.

Science, Space and Technology Committee Chairman Lamar Smith, R-Texas, sent letters Wednesday to some of the state attorneys general leading the probe, and said his committee is ready to use “compulsory” means “to obtain responsive documents in the possession, custody, or control of your office.”