Senate Republicans have refused to allow tax breaks for green energy companies as part of the Federal Aviation Administration reauthorization package, bringing an end to an intraparty debate that unfolded in private over the last several days.

"We've made a decision to skinny down the tax part" of the FAA reauthorization measure, Majority Leader Mitch McConnell told reporters Tuesday.

That's a victory for Sen. Jeff Flake, R-Ariz., who led the effort to exclude the green energy tax extenders. Democrats are steamed, accusing McConnell of breaking an agreement made during the omnibus debate in November. But their leaders plan to vote for the broader FAA package anyway.

Flake has been arguing behind the scenes for McConnell to block the tax extenders since last week and took the pressure public on Monday. "We urge you to resist the temptation to clutter this important legislation with tax extensions aimed at placating a few special interests," he wrote in a letter signed by three other Senate Republicans. "In December, a deliberate decision was made to omit certain credits like those for fuel cells, small wind turbines, and combined heat and power. This latest effort to hastily extend market-distorting tax policies is imprudent."

Democrats cite the December decision as the justification for adding the tax credits now.

"During the omnibus negotiations McConnell agreed to include the clean energy provisions on a fast-moving finance vehicle, i.e. the FAA bill," according to a Senate Democratic aide. "Republican resistance led him to include a tax benefit for beer distributors to try and shore up Republican support. We continue to try and find a way to help him navigate the issues within his conference, and we are trying very hard to be flexible and productive, but at the end of the day this is a commitment Senator McConnell made and it's up to him to keep his word."

McConnell's team told Democratic leadership on Tuesday morning that 20 Republicans would vote for the green energy provisions, according to Senate Democratic leader-in-waiting Chuck Schumer, but conservative activists provided outside support to Flake.

"We urge you to vote NO on FAA re-authorization if subsidies for renewable energies are included," the free market group Americans for Prosperity, which is backed by the Koch brothers, wrote in a letter to senators on Tuesday. "These types of handouts have consistently failed to deliver on their promises of long term job creation and economic viability, and they follow the $24 billion in tax credits to wind and solar energy industries that Congress extended just four months ago."

Schumer blamed the Koch brothers for the failure of the green energy provisions. "It's highly likely if every Democrat voted for the tax provision there would not have been 60 votes, they were short of votes desperately," the New York Democrat said. "Particularly after the Koch brothers made it clear they are against any modifications in terms of clean energy no matter what is added in the bill."

Another free market group supported by the Kochs celebrated the blockade of the green energy tax credits as a defeat for cronyism.

"Americans oppose corporate welfare and they're tired of lawmakers handing out special benefits to the well-connected," Freedom Partners Senior Policy Adviser Andy Koenig said in a Tuesday statement. "When Washington tries to bury billions in special interest giveaways into any legislation, Freedom Partners will continue to shine a spotlight on it. Congress is right to reject this backroom deal and move ahead with a clean FAA extension."

Kyle Feldscher contributed to this report.