ABC News(WASHINGTON) — The federal government shutdown has entered its second day and lawmakers remain stymied on even a short-term funding solution — a standoff that could drag on into the start of the work week on Monday.

The legislative impasse could impact thousands of federal workers and the citizens they serve, as staffing at most agencies would be cut to a fraction of normal levels. Director of the Office of Management and Budget Mick Mulvaney sent a memo to the leaders of federal agencies and executive departments on Saturday urging them to prepare. There is no “clear indication that Congress will act in time” to fund the government by Sunday night, the memo said.

The last government shutdown cost America $24 billion, or $1.5 billion a day, according to Standards & Poor’s estimates.

Stalemate on immigration

Back on Capitol Hill, Democrats and Republicans are digging in their heels, refusing to back off from their demands.

Republicans put forth a three-week short-term bill to fund the government through Feb. 8, but Democrats are seemingly not yet willing to make a deal.

At issue: the future of 800,000 undocumented immigrants who came to the U.S. as children. Democrats want protections for Deferred Action for Childhood Arrivals (DACA) recipients attached to a must-pass spending bill, but Republicans insist that’s not going to happen.

Republicans maintain that DACA and immigration reform must be handled separately from government funding, and are unwilling to negotiate until the government is reopened.

Threats to use the “nuclear option”

In a Sunday-morning tweet, Trump accused Democrats of wanting illegal immigrants to “pour into our nation unchecked” and suggested Republicans should use the “nuclear option” — changing longtime Senate rules to allow a simple majority vote of 51 rather than 60 — to vote on a long-term budget if the shutdown continues.

There are currently 51 Republicans and 49 Democrats, including two independents who tend to caucus with that party.

Senate Majority Leader Mitch McConnell vowed that the short-term measure will have its day on the floor, even after Democrats rebuffed his efforts to advance the bill.

“Earlier today, I asked for consent to move up a vote on this bipartisan solution and end this craziness today. The Democrats objected. That won’t work forever. If they continue to object, we cannot proceed to a cloture vote until 1:00 a.m. on Monday. But I assure you, we will have the vote at 1:00 a.m. on Monday, unless there is a desire to have it sooner,” McConnell said on Saturday.

The cloture vote will end debate on the Feb. 8 short-term funding measure, and it will need 60 votes in the Senate to pass — meaning it would need some Democratic support unless the “nuclear option” is used.

Mulvaney weighed in on the nuclear option on CNN’s State of the Union on Sunday, describing the nuclear option as one option to break the stalemate.

“We’ve been critical of that 60-vote rule since the president took office. And I think what the president did this morning is tried to shed some light on the fact that if ordinary rules prevailed, the majority ruled in the Senate, the government would be open as of today,” Mulvaney said.

House Speaker Paul Ryan on Face the Nation on Sunday said the House stands ready to pass the three-week extension if the Senate is able to pass the measure.

“We have agreed that we would accept that in the House, and so we will see some time today whether or not they have the votes for that,” he said. “And that’s really where we are right now.”

Blame game and negotiations continue

Meanwhile, Democrats continued to blast away at the White House, saying “this shutdown is almost entirely the making of the president.”

“Negotiating with President Trump is like negotiating with Jello. That’s why this compromise will be called a Trump Shutdown,” the Senate’s top Democrat Chuck Schumer said Saturday afternoon.

As late as Saturday evening, some senators involved in a bipartisan bill to shield DACA recipients were seen shuffling between McConnell’s and Schumer’s offices, suggesting that talks are still ongoing. Aides confirmed to ABC News that President Trump and McConnell remained in contact speaking by phone throughout the day.

“Senate Republicans remain ready and eager to end this manufactured crisis. This is not a crisis — it’s a manufactured crisis,” McConnell said on the floor. “We voted to avoid it entirely in our bipartisan vote last night. We are ready to vote again. All the country needs is for the Democratic leader to withdraw his filibuster and let a bipartisan majority pass this bill and reopen the United States government.”

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