Senate Republicans on Monday blocked a mammoth defense policy bill, throwing the legislation into limbo as Congress heads into a packed year-end schedule.

The Senate voted 45-51 to start winding down debate on the National Defense Authorization Act (NDAA), which sets spending levels and policy for the Pentagon. But that is short of the 60 votes needed to overcome the hurdle.

Sen. Susan CollinsSusan Margaret CollinsGraham emerges as go-to ally for Biden’s judicial picks On The Money — Biden sticks with Powell despite pressure Senators call for Smithsonian Latino, women’s museums to be built on National Mall MORE (Maine) was the only Republican to vote with Democrats to advance the bill, while Democratic Sens. Ed MarkeyEd MarkeyEquilibrium/Sustainability — Presented by Southern Company — Pledged money not going to Indigenous causes Senate Democrats call on Biden to push for COVID-19 vaccine patent waivers at WTO The Hill’s Morning Report – Ins and outs: Powell renominated at Fed, Parnell drops Senate bid MORE (Mass.), Jeff MerkleyJeff MerkleyLawmakers call on Olympic committee to press China on human rights abuses Senate Democrats call on Biden to push for COVID-19 vaccine patent waivers at WTO The Hill’s Morning Report – Ins and outs: Powell renominated at Fed, Parnell drops Senate bid MORE (Ore.), Elizabeth WarrenElizabeth WarrenRestless progressives eye 2024 Poll: Harris, Michelle Obama lead for 2024 if Biden doesn’t run Biden eyes new path for Fed despite Powell pick MORE (Mass.) and Ron WydenRonald (Ron) Lee WydenLobbyists turn to infrastructure law’s implementation Democrats plow ahead as Manchin yo-yos Overnight Energy & Environment — House passes giant climate, social policy bill MORE (Ore.) and Independent Sen. Bernie SandersBernie SandersRestless progressives eye 2024 Key senators to watch on Democrats’ social spending bill Five ways Senate could change Biden’s spending plan MORE (Vt.) voted against moving forward along with 46 GOP senators.

The setback comes amid a stalemate on allowing votes on amendments to the bill. Leadership previously got a deal before the Thanksgiving recess to allow for 18 amendment votes, but that agreement was blocked by several Republicans who didn’t get their own proposals included. 

Democrats are leaving the door open to trying to move the bill again. Senate Majority Leader Charles SchumerChuck SchumerDemocratic frustration growing over stagnating voting rights bills Schumer mourns death of ‘amazing’ father Feehery: The honest contrarian MORE (D-N.Y.) took steps on Monday night to make it easier to force the vote for a second time.

“Republicans just blocked legislation to support our troops, support our families, keep Americans safe. Republican dysfunction has again derailed bipartisan progress,” Schumer said from the Senate floor, calling the GOP stance “inexplicable and outrageous.”

“Despite this vote, Democrats will continue to work to make sure our troops get paid and our vital defense programs can continue,” Schumer added.

But Republicans are accusing Schumer of trying to jam the defense bill through the Senate after delaying bringing it to the floor. It can take up to two weeks to bring the defense bill up for debate and get it to a final vote.

The Senate Armed Services Committee voted to advance the defense bill in July, and the delay in bringing it before the full Senate for a vote sparked frustration from Senate Republicans and House Armed Services Committee Chairman Adam SmithDavid (Adam) Adam SmithOn steel and aluminum trade, Trumpism still rules Overnight Defense & National Security — Presented by Boeing — Pentagon vows more airstrike transparency Schumer strikes deal with House, dropping push to link China, defense bills MORE (D-Wash.).

“No matter how important it is, that doesn’t mean that we’ll accept the fact that Sen. Schumer wants to jam it through the Senate without adequate consideration. Let me be clear: Sen. Schumer has put us in this position today. He waited more than two months after we filed the NDAA to bring it to the floor. Two months,” said Sen. James InhofeJames (Jim) Mountain InhofeOvernight Defense & National Security — Presented by Boeing — Pentagon vows more airstrike transparency Senate GOP threatens to block defense bill    Outcry grows over Russian missile test that hit satellite MORE (Okla.), the top Republican on the Armed Services Committee.

As part of the deal that leadership tried to clear before the break, the Senate would have voted on 18 amendments, with Schumer noting that Inhofe and Armed Services Committee Chairman Jack ReedJack ReedBiden administration resists tougher Russia sanctions in Congress Overnight Defense & National Security — Presented by Boeing — Senate punts on defense bill Warren calls for Senate probe of 2019 Syrian airstrike that killed dozens of civilians MORE (D-R.I.) had also worked out a deal to include at least an additional 50 amendments in the bill without needing a vote on each proposal. Of the 18 amendment votes, 11 were either GOP amendments or bipartisan amendments.

But several Republican senators blocked that package. And Senate Minority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellFive issues that will define the months until the midterms  Key senators to watch on Democrats’ social spending bill Republicans seem set to win the midterms — unless they defeat themselves MORE (R-Ky.) on Monday pointed to several issues that Republicans want additional amendment votes on that were not part of the 18-amendment package offered before the Thanksgiving break. They include a proposal for sanctions related to the Nord Stream 2 pipeline, which has the backing of GOP Sens. James Risch (Idaho) and Ted CruzRafael (Ted) Edward CruzGermany calls on Congress not to sanction Nord Stream 2 pipeline: report Fauci says lies, threats are ‘noise’ Biden administration resists tougher Russia sanctions in Congress MORE (Texas). The House-passed defense bill included Nord Stream 2-related sanctions.

“The Democratic leader seems to want to put national security last. My colleague is trying to overcorrect for poor planning by cramming a two-week bill into two or three days’ time. I imagine there might be finger-pointing at Republicans if that proves impossible,” McConnell said.

“Nothing less than the safety of the American people is at stake. This is more important than political timetables for partisan wish lists,” he added.

In addition to the pipeline, Republicans want votes on amendments related to support for Ukraine and China.

A White House official told The Hill that the administration is working with lawmakers “on a legislative package of sanctions in the event Russia invades Ukraine further” with an aim at placing maximum penalties on Russia without alienating European allies. Axios previously reported that the German government had urged Congress not to impose Nord Stream 2 pipeline sanctions and voiced concerns that doing so would “damage transatlantic unity.”

“We’re seeing some members of Congress press for sanctions that that don’t actually deter Russia but do threaten Transatlantic unity, in order to score political points at home — all while holding up critical national security funding on a range of unrelated issues. It makes no sense,” the official added to The Hill. 

But the pathway for the defense bill is unclear. Typically, the House and Senate each pass their version of the bill and then enter formal negotiations to come up with a final deal. Once that happens, the two chambers pass the final agreement and send it to the White House for the president’s signature.

Congress has to pass separate legislation this week to fund the government by the end of Friday in order to prevent a shutdown, likely punting the defense bill until at least next week absent an agreement.

It also faces a mid-December deadline for raising the nation’s debt ceiling, and Democrats want to pass President BidenJoe BidenBiden to provide update Monday on US response to omicron variant Restless progressives eye 2024 Emhoff lights first candle in National Menorah-lighting ceremony MORE’s climate and social spending bill by the end of December.

Reed indicated that lawmakers could look for alternative paths to reaching a final deal on the defense bill by the end of the year. Aides had floated earlier Monday that the House and Senate could work out a deal without going to a formal conference that would then be taken up by the Senate.

“We will have to do the NDAA. It will be done. I think Sen. Inhofe is committed to that, as I am. And we’ll have to use procedures that are appropriate to get it done,” Reed said. “But we just missed an opportunity to send a clear message that we support this legislation.”

Updated at 9:28 p.m.