"There is pledge fatigue"

Mr. Norquist said that those who raise questions about the pledge often do not understand it. “The pledge specifically says you can eliminate tax deductions if you bring rates down at same time,” he said. “The people who say that the pledge would get in the way of tax reform, well their point is they want a tax increase.”

But confusion over the fine points of tax policy is the subject of hot debate in the Senate cloakroom, said Al Hoffman Jr., a Republican fund-raiser and former finance chairman for the Republican National Committee. “Several members of Congress have told me privately that they are wrestling with how to deal with this,” he said.

“The smart Republicans realize that if we’re ever going to reconcile with the Democrats and come to a compromise, this is their holy grail,” Mr. Hoffman said. “They want loopholes eliminated and we should call their bluff because many Democrats have lobbied for corporate loopholes too.”

He said that changes in tax policy were also needed to make large-scale changes to entitlement programs. “If we don’t, we’ll be dead in the water and we won’t be able to beat Obama.”