WASHINGTON — The Senate is scheduled to have a key vote at noon Monday on a bill to reopen the government and fund it for three weeks, though it’s unclear if this plan will win over enough Democrats to pass.

The vote will come several hours after the workday for hundreds of thousands of furloughed federal employees was supposed to have begun, and comes three days after the government officially shut down Friday at midnight. Many of the shutdown’s full effects were less visible during the weekend, when much of the federal workforce would typically be off anyway.

The vote was moved from 1 a.m. ET Monday to noon after it became clear Democrats would block the spending bill over disagreements on a variety of issues, most notably what do about young people affected by the Deferred Action for Childhood Arrivals program.

Senate Majority Whip John Cornyn of Texas said he thought Senate Minority Leader Chuck Schumer of New York agreed to push back the vote to give his caucus “a chance to chew” on a GOP proposal to break the impasse.

“It’s better to have a successful vote tomorrow at noon than a failed vote tonight,” Cornyn told reporters.

But a top Democratic leadership aide disputed Cornyn’s assertion and said unless Republicans make significant changes to their offer, Democrats will likely reject it when the vote comes. The Democratic aide did say, however, that progress was made in the lengthy negotiations that took place late Sunday night. But more talks are needed.

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GOP Sen. Jeff Flake told reporters Sunday night a bipartisan group of senators will meet again at 10 a.m. ET Monday ahead of the noon vote.

He said he was now a “yes” on the funding bill and it was his hope that six or seven more moderate Democrats would come on board to get the continuing resolution over the finish line — to 60 votes — to end the shutdown.

He said the Democrats still want something tangible on DACA but said it was problematic because it could run into the February 8 funding deadline.

He argued that they won a concession from Senate Majority Leader Mitch McConnell that he isn’t requiring President Donald Trump to sign off before an immigration bill moves to the floor.

“For the first time, we have the majority leader move off of we can only move something if the President agrees,” Flake told reporters.

Despite Schumer’s rejection of the deal, one senior GOP aide involved in the talks told CNN Republican leaders think they have a shot of picking off enough Democrats to move forward.

While McConnell’s commitment falls far short of what the vast majority of Democrats want, there’s some GOP hope they can get enough to move forward — and notably split the caucus.

“This is their off-ramp,” the aide said. “We’ll see if they dig in or if they want a way out.”

The aide also noted talks will continue and may yield more progress in the meantime.

Earlier Sunday, Trump called for Senate Republicans to change the chamber’s rules to resolve the funding impasse as the government shutdown continued into its second day. He tweeted a call for McConnell to invoke the so-called “nuclear option” and thereby remove leverage for Senate Democrats.

Senate rules impose a threshold of 60 votes to break a filibuster, and Senate Republicans currently hold a slim majority of 51 votes, meaning even if they can unite their members, they need nine more votes to end debate. The White House is calling for the Senate to change its rules and move the threshold to a simple majority of 51 votes.

A spokesman for McConnell said in response to the tweet that the Senate Republican Conference does not support changing the 60-vote rule, a reiteration of Republican Senate leadership’s already-stated opposition to the move Trump has called for over the past year.

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