(WASHINGTON) -- Democratic congressional leaders are facing a progressive revolt -- that could potentially risk a government shutdown -- in the wake of the closed-door deal between Senate Majority Leader Chuck Schumer and West Virginia Sen. Joe Manchin that won the latter's crucial support for the Inflation Reduction Act.
After repeatedly slamming that "disastrous side deal" that would streamline the permitting process for energy projects across the U.S. -- which Schumer agreed to include with a must-pass spending bill to fund the federal government -- Sen. Bernie Sanders, I-Vt., promptly announced Thursday that he intends to oppose the funding resolution as a result.
"If the United States Congress goes on record and says, 'Yes we are going to support more fossil fuel reduction, more carbon emissions,' the signal we are sending to our own people and the planet is a terrible, terrible signal," Sanders said in a floor speech.
He did not mince words with reporters afterward. Asked if he would vote no on funding the government if the Schumer-Manchin permitting deal is attached, he replied: "Yes. You're talking about the future for the planet."
Sanders' opposition adds to the growing progressive pressure in the House, where some left-wing lawmakers have likewise threatened to block the government funding bill if it includes Manchin's desired changes to energy permitting.
Sanders on Thursday read from a soon-to-be-released letter -- obtained by ABC News Wednesday -- that he said had been signed by "at least 59" House progressives opposing the Schumer-Manchin agreement.
That deal, Sanders said, quoting from the letter, "would silence the voices of environmental communities by insulating them from scrutiny. This would cause members to choose between protecting environmental justice communities from further pollution or funding the government. We urge you to ensure these provisions are kept out of a continuing resolution or any other must-pass legislation this year."
Manchin has argued that permitting reform will also help speed projects related to wind, solar and other environmentally friendly sources of energy. He's adamant that permitting reform must stay in the funding bill and, so far, he seems to have Schumer's backing.
Despite the progressive rhetorical thunder, it is possible that the bill to fund the government -- which will also include popular aid for Ukraine and disaster relief -- will garner enough GOP support to render the threatened liberal blockade moot.
"It was a rank political deal," Sen. Richard Shelby, the top Republican on the appropriations committee, told reporters Thursday of Manchin and Schumer's agreement. But he stopped short of saying it would put government funding in jeopardy.
Still, some other Republicans are vowing to oppose the funding resolution because they oppose Schumer and Manchin's dealmaking. Many conservatives have said they took umbrage at the last-minute nature of the deal among Democrats on the sweeping climate and health care reform legislation known as the IRA. It passed without a single GOP vote -- not long after some Republicans had voted with Democrats on computer chip funding, thinking that the Democrats' social spending bill was dead.
Sen. Lindsey Graham, R-S.C., told ABC that "I would vote against it," referring to government funding, and he said he was urging his Republican colleagues to do the same.
It's not yet clear whether Republicans will unite behind Graham's effort, but most GOP aides familiar with the matter say they do not expect that.
ABC News' Mariam Khan contributed to this report.