WASHINGTON — The Senate is preparing for a crucial vote as early as Sunday night on a proposal that could significantly move toward ending the ongoing government shutdown.

This vote serves as a pivotal measure to determine if enough Democratic senators will join their Republican counterparts to overcome the current deadlock. However, it comes without an extension of Obamacare subsidies that are set to expire by year-end, a key point Democrats have been firm on during the 40-day shutdown, the longest in the nation’s history.

Insiders have informed ABC News’ Jonathan Karl that the proposed legislation seeks to extend government funding until January 31, while also allocating finances for the rest of the fiscal year to agencies such as the Department of Agriculture, ensuring the continuation of SNAP benefits, and the Department of Veterans Affairs.

A senior Democratic senator disclosed to Karl that there will likely be ample Democratic support to pass the bill, although it is expected that the majority of Democrats, especially those in leadership positions, will oppose it.

Under this plan, Democrats would not gain any immediate advancements on healthcare issues, aside from a commitment that the Senate will address the topic of extending Affordable Care Act subsidies before the year concludes. This mirrors an earlier offer from Senate Majority Leader John Thune, which Democrats had previously rejected.

Although most Senate Democrats are likely to oppose this bill, they are resigned to the fact that this part of the fight is over, sources said. They will take the battle over health care to the midterms and argue that Republicans refused to do anything for the millions of Americans who will see their health insurance premiums skyrocket.

At least 60 votes are needed to move the bill forward. In past votes, Sen. Rand Paul was the only Republican to vote against the bill while Democrats Catherine Cortez Masto and John Fetterman, as well as Independent Angus King, voted for it. At least five more Democrats would have to vote in favor of the bill to move it forward.

Passage of the bill would not immediately reopen the government. The House would also have to approve the bill. The House has been out of session since September and Speaker Mike Johnson would need to call his members back to Washington to consider this bill before it could head to President Donald Trump’s desk.

The Senate wants to modify the bill in a number of ways. Should the vote succeed, it would start debate of the funding bill. If Democrats allow debate to begin, there are some key modifications that senators want to make to the bill:
-They want to change it’s expiration date from Nov. 21 to the end of January.
-They want to attach three full-year funding bills to it. The government is usually funded through 12 full-year appropriations bills. The three that senators hope to include are Military Construction and Veterans Affairs, the Legislative Branch, and the Department of Agriculture. If lawmakers fail to fund the government by the new deadline, programs covered by these bills would be fully funded through the end of the fiscal year.
-There could be the inclusion of some sort of language guaranteeing Democrats a vote by a certain date on a bill to address health care. There could also be some sort of language to reverse some of the administration’s reductions in force of government workers that occurred during the shutdown.

Unless there’s total agreement by all senators to quickly adjust the bill, it could take the Senate up to a week to process it.

ABC News’ Jonathan Karl contributed to this report.