Anti-tax advocate Grover Norquist’s influence over Senate Republicans slipped Tuesday, a development that could have implications for bipartisan budget talks as well as for the future of the party’s orthodoxy.

For decades, Norquist’s anti-tax pledge has dominated Republican politics, with most party members vowing — at Norquist’s behest — to never raise taxes or to offset any tax increases wtith tax cuts elsewhere.

But the No. 3 Senate GOP leader said Tuesday that eliminating tax breaks might be a legitimate way to solve the nation’s current fiscal crisis. “My view is a good way to reduce the debt is to get rid of unwarranted tax breaks,” GOP Conference Chairman Lamar Alexander (Tenn.) said.

Those comments came amid the Senate’s consideration Tuesday of Sen. Tom Coburn’s amendment to eliminate ethanol tax subsidies and cut the deficit by $3 billion. Though Norquist had originally called the proposal a tax increase, 34 Republicans voted with the Oklahoma Republican — albeit after Norquist gave Republicans unusual dispensation to vote for it. He did so after conservative momentum for the measure threatened a direct repudiation of his tax purity test.

But there was a caveat. Norquist told Senators they could vote for Coburn’s proposal only if they also promised to vote for an amendment by Sen. Jim DeMint (R-S.C.) that would eliminate ethanol mandates as well as the estate tax. However, the DeMint amendment might never get a vote and is almost certain to fail even if it does.

Coburn’s bid for a filibuster-proof 60-vote majority failed 40-59 after Democratic leaders whipped against it. Because some Democrats who support the proposal agreed to oppose it on procedural grounds, Democratic leaders promised they would bring up another version of the ethanol amendment next week.

Asked about Norquist’s contention that Coburn’s amendment is a tax increase, Alexander said, “This is a vote for lower food prices and lower federal debt.”

And Minority Whip Jon Kyl (Ariz.), who is the Senate negotiator in debt limit talks led by Vice President Joseph Biden, said he supports killing the special tax provision as well.

“I’m just looking at it from the standpoint of tax policy. We shouldn’t be picking winners and losers,” Kyl said.

The issue goes far beyond ethanol. Coburn and Norquist — who heads the advocacy group Americans for Tax Reform — are engaged in a grudge match over whether eliminating tax breaks can be part of an overall deficit reduction package.

The drama behind the vote included a visit from Norquist to brief 60 Senate staffers Tuesday, which one Senate aide said grew contentious.

The battle also appeared to set up a struggle for the heart of Republican politics between the conservative Club for Growth and Norquist’s group. The club, which is widely feared because of its ability to successfully defeat GOP incumbents in primaries, announced last week it would make Coburn’s amendment a key vote. And after Americans for Tax Reform announced the DeMint maneuver, the club put out a statement Monday in which it backed the DeMint amendment but said it supports Coburn’s amendment regardless — a clear rebuke of Norquist’s position.

Many Republicans said Tuesday that they consider items such as the ethanol provision to be a spending program dressed up as a tax break.

“I just disagree with [Norquist’s] interpretation,” said Sen. Pat Toomey (Pa.), a former head of the Club for Growth.

“Look, Grover has accomplished something significant in his whole pledge, and the priority it’s been given has been a useful tool in uniting Republicans behind the principle of lower taxes. But I don’t know that there’s any Republican more committed to lower taxes and pro-growth policies than I’ve been,” Toomey said.

Sen. Richard Shelby (R-Ala.) also rejected Americans for Tax Reform’s position that eliminating the program amounts to a tax increase. “Grover Norquist has a lot of good ideas, but I disagree with him on this. … I agree with the Club for Growth.”

Even National Republican Senatorial Committee Chairman John Cornyn (Texas) agreed that eliminating subsidies “hardly is the same thing as raising taxes.”

Norquist also favors eliminating the ethanol credit, but only if it is offset with a tax cut somewhere else.

Ryan Ellis, tax policy director for Americans for Tax Reform, dismissed the Senators’ comments.

“The pledge is not about what Senators say but how Senators vote,” Ellis said, predicting that the Senators would have voted for both Coburn and DeMint if given the opportunity.

“They would have been just fine with the pledge,” Ellis said. “It’s about, ultimately at the end of the day, how these guys vote.”

DeMint said the tax pledge was “important” but that he offered his amendment to get out of having to choose between breaking the pledge and backing Coburn.

But Sen. John Thune (R-S.D.), who opposed the Coburn amendment, accused Norquist of making up a new set of rules for his pledge to give cover to Republicans who backed the Coburn amendment.

“It’s a whole new interpretation of the pledge, which I think is going to make the pledge less and less relevant,” he said.

If the position of Coburn and others holds, it could provide an opening to include revenue in a broader budget deal in return for Democrats walking the plank on spending cuts.

Democrats said the Senate vote could be a harbinger of things to come.

Rep. Chris Van Hollen (D-Md.), one of the negotiators in the bipartisan Biden talks, applauded Coburn’s effort.

“His willingness to cut special interest tax breaks for the purpose of deficit reduction is encouraging,” he said. “Instead of cutting investments in education and infrastructure, we need to look at cutting other corporate pork like wasteful subsidies for the oil and gas industry.”