The FEC is asking questions about campaign contributions to Adam Laxalt and Catherine Cortez Masto.
Government watchdog OpenSecrets reports that the Cortez Masto and Laxalt campaigns have raised $52.9 million and $15.5 million, respectively, as of October 19.
Campaigns must adequately respond to the inquiries or face potential action by the FEC, including audits, investigations, and fines.
The FEC reached out to Warnock rival Herschel Walker's campaign in March regarding excessive contributions from 17 supporters.
Cortez Masto has until December 12 to respond to the FEC.