A Federal Reserve rule capping debit card “swipe” fees set by Visa Inc. and MasterCard Inc. would be delayed at least six months under a plan introduced Tuesday in the U.S. Senate, Bloomberg reported.

Senators began considering language from Sen. Jon Tester, a Montana Democrat, and Sen. Bob Corker, a Tennessee Republican, that would let federal regulators study the issue before determining whether to write new rules. The caps, mandated by the Dodd-Frank Wall Street Reform and Consumer Protection Act, were originally to go into effect April 21 but have already been moved back to July 21.

Dave Nelson, chairman and CEO of West Bank in West Des Moines, said the proposal, which would establish rate caps for banks with more than $10 billion in assets and exempt those below that level, will lead to de facto caps for all banks. The majority of banks operating in Greater Des Moines, including West Bank, are below that threshold.

“We all use the same network,” Nelson said. “To say that certain fees can be fixed at one tier and not another, it just won’t work that way. They’re now realizing that the carve-out for smaller banks just won’t work. I’m not aware of any of any example where government price fixing has worked in the history of the country, and this is price fixing.”

The Fed would get an additional six months to make changes if the study shows the current proposal would hurt consumers or fail to protect banks and credit unions with less than $10 billion in assets. In December, the central bank proposed capping the swipe, or interchange, fees or interchange, at 12 cents a transaction, replacing a formula that averages 1.14 percent of the purchase price.

The new proposal calls for the Fed, the Federal Deposit Insurance Corp., the office of the Comptroller of the Currency and the National Credit Union Administration to conduct a study that considers all fixed and incremental costs of debit card transactions. If at least two study participants determine that the rules don’t accurately reflect those costs or properly exempt smaller banks and credit unions, the Fed would be required to rewrite them.