House Republicans are threatening “formal action” against the Environmental Protection Agency unless the agency hands over records about Administrator Lisa Jackson’s use of a secondary government email account.

Republicans allege that Jackson’s use of an internal account under the alias “Richard Windsor” undercuts the agency’s transparency.

Top Republicans on the Science, Space and Technology Committee sent the EPA a letter Thursday that says the agency has failed to comply properly with prior requests for records about use of “dual, secondary and non-public” email accounts by EPA officials.