A mammoth energy policy bill hit a roadblock in the Senate on Monday night with a stalemate over amendments threatening to derail the legislation entirely.

Lawmakers voted against closing debate on an updated version of the bill that included a package of noncontroversial amendments forwarded by its sponsors, a sign lawmakers are still eager to push for some of the 191 amendments that have been proposed for the bill.

The path forward for the bill, which had been expected to pass as soon as Tuesday, is now unclear. Senate Majority Leader McConnell (R-Ky.) did vote against it, a procedural tactic that could allow him to try to end debate for a second time if he’s able to reach a deal.

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Senate Majority Whip John Thune John Randolph ThuneThe Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon The Hill's Morning Report - Sponsored by The Air Line Pilots Association - Trump contradicts CDC director on vaccine, masks Senate GOP eyes early exit MORE (R-S.D.) said negotiations had stalled on a path forward on amendments.

"We'll probably end up having to pivot something else, until we figure out if there's a way we can get this back on track," Thune told The Hill.

The American Energy Innovation Act, sponsored by Sens. Lisa Murkowski Lisa Ann MurkowskiGOP ramps up attacks on Democrats over talk of nixing filibuster OVERNIGHT ENERGY: House Democrats tee up vote on climate-focused energy bill next week | EPA reappoints controversial leader to air quality advisory committee | Coronavirus creates delay in Pentagon research for alternative to 'forever chemicals' House Democrats tee up vote on climate-focused energy bill next week MORE (R-Alaska) and Joe Manchin Joseph (Joe) ManchinBiden promises Democratic senators help in battleground states Senate leaders quash talk of rank-and-file COVID-19 deal OVERNIGHT ENERGY: House Democrats tee up vote on climate-focused energy bill next week | EPA reappoints controversial leader to air quality advisory committee | Coronavirus creates delay in Pentagon research for alternative to 'forever chemicals' MORE (D-W.Va.) would spur research and development into a number of types of energy, the first major package on the topic in more than a decade.

Democrats have been fighting to add amendments that would phase down the use of heat-trapping hydrofluorocarbons (HFCs) used in refrigerators and air conditioners, as well as another that could push to make new homes more energy efficient.

The White House and a few senators have expressed opposition to the HFCs amendment, arguing that federal standards should supersede any passed by the states.

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But Senate Minority Leader Charles Schumer Chuck SchumerMcConnell accuses Democrats of sowing division by 'downplaying progress' on election security Warren, Schumer introduce plan for next president to cancel ,000 in student debt Schumer lashes out at Trump over 'blue states' remark: 'What a disgrace' MORE (D-N.Y.) threatened to filibuster the bill hours ahead of Monday night’s votes, accusing McConnell of blocking an otherwise popular amendment from Sens. John Kennedy John Neely KennedyMORE (R-La.) and Tom Carper Thomas (Tom) Richard CarperDemocrat asks for probe of EPA's use of politically appointed lawyers Overnight Energy: Study links coronavirus mortality to air pollution exposure | Low-income, minority households pay more for utilities: report OVERNIGHT ENERGY: Democrats push resolution to battle climate change, sluggish economy and racial injustice | Senators reach compromise on greenhouse gas amendment stalling energy bill | Trump courts Florida voters with offshore drilling moratorium MORE (D-Del.) that could help fight climate change.

“They’re thousands of times more damaging to our atmosphere than carbon dioxide. Phasing out these HFCs is very important. And it will go a long way in fighting climate change and protecting the environment for future generations,” he said, calling the energy bill “a real rare opportunity to make tangible progress.”

But even with numerous Republicans crossing the aisle to continue the debate, Senate Minority Whip Dick Durbin Richard (Dick) Joseph DurbinMcConnell focuses on confirming judicial nominees with COVID-19 talks stalled Senate Republicans signal openness to working with Biden Top GOP senator calls for Biden to release list of possible Supreme Court picks MORE (D-Ill.) said they had gotten no sign from Republicans that they are willing to give Democrats the amendment votes they want.

“We don’t know yet, we don’t know,” Durbin said as he left the Capitol for the day, asked what’s next for the energy bill.

Sen. John Barrasso John Anthony BarrassoOVERNIGHT ENERGY: Democrats push resolution to battle climate change, sluggish economy and racial injustice | Senators reach compromise on greenhouse gas amendment stalling energy bill | Trump courts Florida voters with offshore drilling moratorium Senators reach compromise on greenhouse gas amendment stalling bipartisan energy bill The Hill's Morning Report - Sponsored by National Industries for the Blind - Trump, Biden battle over vaccine, economy; Congress returns MORE (R-Wyo.) has been the lead Senate voice pushing back against the HFC provision, arguing it should have passed through his committee and should also contain preemption language that blocks states from setting any standards on HFCs that might be stricter than those of the federal government.

“This is trying to airdrop something into the energy bill that's been referred to another committee. The idea of having committees is to vet ideas,” Barrasso told The Hill on Thursday. “They chose to bypass the committee process and ignore some of the suggestions or have not yet accepted some of the suggestions that I think would help improve it.”

Barrasso and Kennedy said Thursday they were working together on a compromise, but Kennedy has repeatedly expressed frustration that his amendment might be held back from a vote because of complaints from a handful of senators.

"It doesn't mean you have to vote for it," he said on the floor last week. "You can vote against it. But please let the entire body have a vote. Because that is what democracy is supposed to be about."

Manchin, ranking member of the Energy and Natural Resources Committee, was likewise irritated by the holdup Monday night.

“This is the most legislating this body has done this entire Congress," Manchin said in a late evening statement. "It’s a shame the good work of the Energy and Natural Resources Committee was impacted by the Environment and Public Works Committee's inability to reach consensus. We will continue to put in the work to get this bill across the finish line."