It also comes as the July 21 deadline for the limits to take effect draws close.
Under the new amendment, if the Federal Reserve -- which is required to write rules implementing the new limits -- and another financial regulator determine the provision fail to account for all costs, adversely affect debit card users, or cannot exempt small banks, then the Fed would be required to rewrite the rules over a six month period.
If regulators do not come to those conclusions, the Fed is free to move forward with its currently proposed rules -- which would slash the fees banks can charge retailers for using debit cards from the current industry average of 44 cents to seven to 12 cents per transaction.
In addition, the amendment would require regulators to revist the small bank exemption two years later to make sure it is still working properly, and report those findings to Congress.
Retailers immediately launched into strong opposition to the amendment as it was being rolled out on the Senate floor, calling it a handout to banks.
"While proponents try to cast this amendment as a 'compromise,' it is just the opposite," said Sandy Kennedy, president of the Retail Industry Leaders Association. "The Tester/Corker Amendment is a remarkable giveaway to big banks and credit card companies at the expense of merchants and consumers, pure and simple. "
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Bernie Becker contributed to this report.