WASHINGTON — In the lobbying equivalent of the Yankees and Red Sox joining forces, the heads of the two biggest credit union trade associations and the two largest bank groups convened in a Washington restaurant Wednesday night to show off a new TV ad  aimed at urging lawmakers to delay the new interchange rule. 

The ad, which will air on broadcast and cable stations in the Washington, D.C. area, talks about the domino effect on consumers from the "$12 billion payday'' that Congress gave retailers when it mandated that the Fed write a rule limiting interchange fees.

Trish Wexler, a spokeswoman for the Electronics Payments Coalition, declined to say how much money they are spending on the ad buy but said they hope to run the ads "until we win the fight.'' The Federal Reserve rule is supposed to take effect in July but there are bills in the House and Senate that would delay the implementation.