To date, the GOP has embraced lower marginal rates going hand-in-hand with the elimination of some breaks in a “revenue-neutral” formula. Asked repeatedly if he was indeed endorsing a net increase in revenue that was not just attributable to anticipated growth, Grassley said he was.

“Yes,” he said, “but that’s kind of a touchy thing to talk about when [anti-tax lobbyist] Grover Norquist is making the decision of what’s a tax raise, and that’s why I put emphasis on getting economic growth scored.”

Grassley said that the scoring change Republicans would require in order to sign off on such a plan would reap dividends for the GOP’s small-government approach over the long term.

“If you get CBO turned around to dynamic scoring, it will benefit the conservative approach to government and taxes in later years,” the former chairman of the Senate Finance Committee said.