The American Banker (subscription required) reports that Senator Dick Durbin has "added an amendment to an appropriations bill that would require credit card payments accepted at government agencies to be given the lowest available market interchange rates, which typically can only be negotiated by large supermarket chains."
The amount of money at stake is relatively small–perhaps $28 million/year. But it is rather astonishing that the US government doesn't already get rock-bottom interchange rates. If interchange is supposed to reflect the merchant's risk (an argument sometimes made), the US government should be getting the risk-free rate. It hasn't been. Frankly, I'm not sure why the government should settle for getting the best rates available to large supermarket chains-that's not a risk-free rate. If interchange is about risk-based pricing, surely supermarkets should pay a premium over the government?
