House Committee on Science, Space and Technology Chairman Lamar Smith threatened to issue a subpoena if the Environmental Protection Agency continues to refuse to turn over to Congress a host of official emails, cellphone text messages and other communications.

“If EPA continues to withhold emails, text messages and other documents from the committee, I will have no alternative but to consider the use of compulsory process to obtain the requested documents and information,” the Texas Republican told the agency’s administrator, Gina McCarthy in a letter made public Monday.