House Democrats asked the Interior Department’s acting inspector general on Tuesday to investigate whether Karen Budd-Falen, the agency’s third-highest official, played a role in federal approval of the Thacker Pass lithium mine after her husband entered into a $3.5 million financial arrangement with the mine’s developer.

A senior Interior Department official failed to disclose that her husband received $3.5 million in payments from the developer of the Thacker Pass lithium mine, records show. Frank Falen sold water rights from the family’s Home Ranch in northern Nevada in 2018 to Lithium Nevada Corp., a unit