Merchants trumped bankers in a battle for billions Wednesday as the Senate voted to let the Federal Reserve slash fees that stores pay financial institutions when customers pay with debit cards.

Whether consumers will see any of that money remains to be seen.

The Fed will now issue its final rules on debit fees, called interchange fees, on July 21. It has recommended cutting the average 44 cents that banks and credit unions charge for each debit card transaction to no more than 12 cents, although the final plan could change slightly.

The fee is now typically 1 to 2 percent of each purchase. It produces $16 billion in annual revenue for banks, credit unions and the credit card companies that operate the huge payment networks, the Fed estimates.

Merchants say lower fees should let them lower prices. Banks warn that they'll have to recoup the lost revenue through other charges that likely will come directly from consumers' pockets, such as higher checking account fees.