WASHINGTON — Don't look now, but it appears the issue of credit card interchange may be reappearing on the national agenda.

Credit card interchange is the amount of money the credit card brands charge retailers to take their cards. It is usually charged on a transaction basis and its rate can depend on a wide variety of factors, ranging from how many transactions a retailer has in a given period to the type of card the customer uses to the type of product they buy.

The card brands have historically justified charging interchange as a way to recoup the costs of bringing the cards to market, as well as covering the cost of processing, maintenance, fraud and fraud prevention. Retailers have long charged that the card brands have unfairly set interchange rates and that the two biggest brands, Visa and MasterCard, are effectively a monopoly who benefit from the unfair pricing.