US Senator Dick Durbin is requesting the Fed probe card networks and issuers, such as Mastercard and Visa.
The senator wants an investigation over potentially anticompetitive fees.
Durbin's letter hi-lighted that merchants are paying excessive debit card fees during the pandemic.
The companies have planned major fee changes for US-based merchants.
The Feds are requesting a competition-based investigating into Visa, Mastercard, and major issuers.