Congress has just hours to pass their massive budget deal and avoid a government shutdown

• The government will shut down at 12:01 a.m. if Congress does not pass a funding bill.
• Senate leaders agreed to large budget deal, but a vote has been up by Sen. Rand Paul.
• It also remains unclear whether the bill will have enough votes to pass the House, as members of both parties have resisted the deal.

Congress scrambled Thursday, hours before the government was set to again enter a partial shutdown while leaders looked to spearhead a massive budget deal through both chambers.

The two-year budget deal would extend current federal funding until March 23, which would allow congressional appropriators time to craft the details of a longer-term plan.

The deal would bump limits on defense and nondefense spending by just under $300 billion combined over the next two years.

But passage of the bill has hit some unexpected snags as Congress races toward the deadline.

In the Senate, Rand Paul, a Republican from Kentucky, has held up a vote. Paul said he is withholding his support for a procedural step that would allow the Senate to move toward a vote on the bill.

Paul insisted in December he would not vote for any "budget-busting" spending bill. An estimate from the Committee for a Responsible Federal Budget projected the agreement would add more than $300 billion to the federal deficit over 10 years.

If Paul continues his objection, he could hold up a vote until about 1 a.m. ET on Friday, one hour after the shutdown deadline.

While there technically would be no federal funding a short lapse wouldn't be a full-blown shutdown, that's only triggered when the Office of Management and Budget sends a memo to federal agencies to initiate their shutdown plans.

Sen. John Cornyn, the second-highest ranking Senate Republican, told reporters that leadership was working toward a solution with Paul.

"I think it will all work out, but it's up in the air," Cornyn said.

Then there is the question of whether or not the budget deal can pass the House.

On one side of the aisle, much like Paul, many Republicans are concerned about the bill's projected effect on the federal deficit. The hardline conservative House Freedom Caucus, which has roughly 30 members, has said most of its members will vote against the legislation.

According to reports, as many as 70 Republicans in the chamber could vote against the bill.

On the other side, Democrats have expressed qualms that the deal does not contain a solution for the Deferred Action for Childhood Arrivals immigration program.

House Minority Leader Nancy Pelosi said she will 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 DACA deal means she will vote against it.

Democratic leadership is telling members to vote against the package. But some Democrats, especially more moderate members, are still expected to vote for the bill.