The massive budget deal is being held up just hours before the federal government is set to enter a partial shutdown.
The Senate voted 71-28 to pass a massive two-year budget deal early Friday morning, less than two hours after the government stumbled into a temporary shutdown.
The deal would extend the current level of federal funding until March 23, allowing congressional appropriators time to craft the details of a longer-term plan. It would also bump limits on defense and nondefense spending by just under $300 billion combined over the next two years.
But the bill hit some unexpected snags, and a shutdown went into effect at 12:01 a.m. ET.
Sen. Rand Paul, a Republican from Kentucky, held up a vote in the chamber, saying he would withhold his support for a procedural step to allow the chamber to move toward a vote on the bill.
Due to procedural rules, Paul held up the spending bill until midnight — also the deadline for the shutdown. He was granted another hour, but yielded it back instead.
After that point, the Senate quickly moved to vote on a motion to bypass a filibuster, which easily passed, and the final vote began. From there, the bill would go to the House for a vote in that chamber — then to President Donald Trump's desk for signature.
House leaders told members to expect a vote on the bill some time between 3 and 6 a.m. ET.
Paul's argument stems from his insistence that he would not vote for any "budget-busting" spending bill. The Congressional Budget Office estimates the agreement would add more than $300 billion to the federal deficit over 10 years.
"We think when Democrats are in charge, the Republicans are the conservative party," Paul said in an interview on Fox News. "The problem is when Republicans are in charge, there's no conservative party, and that's kind of where we are now."
He added: "Someone has to stand up and say, 'You should spend what comes in, we should balance our ledger.' That used to be what it meant to be conservative, but a lot of so-called conservatives lose their mind once it becomes a partisan thing."
Paul said he wanted to vote on an amendment to maintain the current budget caps, the antithesis of the deal and a move that would likely fail, but Senate Majority Leader Mitch McConnell has signaled he will not hold such a vote.
On the Senate floor, McConnell attempted to move forward with the vote via a parliamentary procedure but was rebuffed by Paul. This led to an hours long standoff by Paul, who delivered speeches on the need to trim the federal deficit and sermons on fiscal discipline.
During this stretch, other GOP senators came to the floor to try and break Paul's grip and criticize the move.
"Do you want to be a senator that wants to make a point or you want to make a difference? You know what? I don't see how points alone can make a change in America," Sen. Thom Tillis, a Republican, said on the Senate floor.
A shutdown would be triggered when the Office of Management and Budget sends a memo to federal agencies to initiate their shutdown plans. An OMB official told agencies to be on alert.
When the bill eventually goes to the House, passage is not guaranteed.
Much like Paul, many House Republicans are concerned about the bill's projected effect on the deficit. The hardline conservative House Freedom Caucus has said most of its roughly 30 members will vote against the legislation.
Recent reports suggest that as many as 70 Republicans in the chamber could vote against the bill.
Democrats, meanwhile, have qualms about the deal because it does not address the Deferred Action for Childhood Arrivals immigration program, which is set to end early next month.
House Minority Leader Nancy Pelosi said she would not vote for the bill absent a commitment from House Speaker Paul Ryan to hold an open vote on a DACA solution.
Pelosi also sent a letter to her colleagues saying that while the budget deal secured positive domestic spending goals, the lack of a DACA deal meant she would vote against it.
Rep. Steny Hoyer, the Democratic Whip and second-highest ranking member in the House, asked Ryan to consider a short-term funding bill called a continuing resolution to prevent a midnight shutdown.
"I urge Speaker Ryan to the Floor a one-day funding bill to keep the government open," Hoyer said in a statement. "Given that the Senate still has not passed its bipartisan agreement because Senate Republicans are feuding, time is running short for them to keep the government’s lights on."
While Democratic leadership is telling members to vote against the bill, some Democrats, especially more moderate members, are expected to vote for it.