Washington ? In a heavily lobbied fight pitting financial institutions against merchants, supporters of the nation’s banks pushed Tuesday toward a Senate vote aimed at blocking a government plan to cap the fees that stores must pay banks whenever a customer swipes a debit card.

Both sides claimed to represent consumers’ interests in the high-stakes battle over the $16 billion yearly that the Federal Reserve says stores give banks in those fees. Merchants say the fees force them to charge higher prices and thwart their efforts to grow and add jobs. Banks say the fees are too low because they don’t consider all of their costs in administering debit card programs, and say they’d have to raise other charges — such as for checking accounts — if the swipe fees are reduced.

A showdown vote was set for today. If successful, the provision would block a Fed proposal that would cap the so-called interchange fees at 12 cents per swipe. That’s down from the current average of 44 cents, the result of fees that average between 1 percent and 2 percent per transaction.

Last year’s financial overhaul legislation ordered the Fed to issue a proposal and for a final rule to take effect on July 21. The proposal debated by the Senate would delay the regulations for a year and order the Fed and three other federal agencies to study whether the proposal is fair — and rewrite it if at least two agencies decide it is not.

With merchants and bankers important constituencies and contributors to both Democrats and Republicans, lawmakers’ views on the effort crossed party lines. Sen. Jon Tester, D-Mont., a first-term lawmaker facing re-election in a GOP-leaning state next year, was a leader of the effort to block the cap on fees, while Sen. Richard Durbin of Illinois, the Senate’s No. 2 Democratic leader, was its leading foe.

Durbin, author of the provision in last year’s law that paved the way for the Fed’s plan, said the fight offered senators a clear choice.

“They’re either going to be on the side of the banks and credit card companies, or be on the side of consumers and businesses across the America to give them a fighting chance,” Durbin said.