"I have heard the Federal Reserve say that in some markets you might see people being able to lower pennies, saving on a per item basis, but for the most part, the retailers will keep that difference," said Wexler. "They haven't spent 10 years and hundreds on advertising so they can pass along those savings to those customers."
The cap on interchange fees, said Wexler, would "100 percent result in all of us who own debit cards paying more to use them."
There's been a number of court cases involving card systems, interchange fees and accusations of anticompetitive behavior. In the 1980s, National Bancard Corp filed a suit against Visa for illegal price fixing. A federal district court rejected the suit, according to Bank Accounting and Finance Journal.
In 2003, MasterCard and Visa settled a separate class action on behalf of 4 million retailers, claiming that their card systems injured competition and harmed consumers, the Journal also noted.
"Just because you have two large market players doesn't mean there's something wrong with that. There is plenty of competition in this space," said Wexler, explaining that there are new entrants to the marketplace, especially in e-commerce. "The real problem is the retailers don't want to pay for this."
Mallory Duncan of the National Retail Federation said banking groups are trying to delay the Fed from finalizing its rule by April 21 to give Congress time to "kill" the amendment. According to the NRF, which has 1.6 million American member companies, the banking industry charges $20 billion in debit card swipe fees each year.
Duncan said retailers simply want banks and the card networks to treat debit cards like personal checks, which are not subject to interchange fees.
"The single message is consumers are about to get a huge windfall of about $1 billion a month because the Fed is about to do the right thing -- to move debit cards back into the realm of the plastic checks that they really are. That's all they are. If they delay the process, they're delaying the ability of retailers and restaurants and every other business to give their customers a better deal."