A group accusing the Environmental Protection Agency of shielding official work from public view is suing to obtain the text messages of Gina McCarthy, the senior EPA official President Obama has nominated to run the agency.

The conservative Competitive Enterprise Institute (CEI) filed a lawsuit Wednesday seeking potential messages to or from McCarthy, the agency’s top air pollution regulator, on 18 dates when she testified before Congress.

The lawsuit alleges EPA has not provided the records or a “substantive” response to a late April Freedom of Information Act request, which covers dates McCarthy testified between 2009 and 2012.