Despite intense opposition by credit unions and banks, a bipartisan majority in the Senate last night voted 64-33 to pass an amendment to the regulatory overhaul bill that will restrict interchange fees.

CUNA and NAFCU, both of which launched major grassroots and Washington lobbying efforts, said they would fight to defeat the bill during House-Senate negotiations on the bill. There is no similar amendment in the bill that was passed by the House last year.

The Senate is likely to finish work on the bill next week.

The amendment, sponsored by Senate Majority Whip Richard Durbin (D-Ill.), authorizes the Federal Reserve to ensure that debit card fees are "reasonable and proportional," in relation to processing costs. It excludes credit unions and community banks with assets of less than $10 billion. It also allows merchants to set a minimum or maximum amount for each transaction and let them offer additional discounts for using a certain type of card or cash.

The amendment was supported by 49 Democrats and 17 Republicans. Three members did not vote. The Senate has 57 Democrats, 41 Republicans and two independents who caucus with the Democrats for purposes of organizing the chamber.