By Lauren Fox, Phil Mattingly and Ted Barrett, CNN

(CNN) -- Senate leaders unveiled a two-year budget deal Wednesday, a major victory for both parties that could prevent a government shutdown at the end of this week.

Majority Leader Mitch McConnell unveiled the deal with Minority Leader Chuck Schumer on the Senate floor, which would boost military and non-defense spending by $300 billion over the next two years as well as and more than $80 billion in disaster relief.

"I am pleased to announce that our bipartisan, bicameral negotiations on defense spending and other priorities have yielded a significant agreement," McConnell said.

Schumer was set to speak in favor of the agreement immediately following McConnell, according to the New York Democrat's office.

Just before the deal was formally made public, House Democratic Leader Nancy Pelosi announced she was opposed to it, and while she didn't encourage her caucus to vote "no," her statement raises questions about whether there will ultimately be enough Democratic support in the House to pass the bill.

"This morning, we took a measure of our Caucus because the package does nothing to advance bipartisan legislation to protect Dreamers in the House," Pelosi said in a statement. "Without a commitment from Speaker (Paul) Ryan comparable to the commitment from Leader McConnell, this package does not have my support."

The deal would clear the deck for Congress. If the spending numbers are agreed to, lawmakers could concentrate on tackling other issues like immigration and infrastructure rather than careening from one budget crisis to the next. The bill would also provide long overdue disaster funding for Texas, Florida and Puerto Rico months after hurricanes devastated homes, infrastructure and coastlines there.

Raising the budget caps has been on the table for months but has always been entangled with the contentious immigration debate. Pelosi's statement reveals the deep schisms within the Democratic Party between those willing to show some flexibility now after a three-day shutdown and those who are dug in on immigration.

While the bill is expected to pass easily in the Senate, the House will be a tougher sell. The caps deal will likely need Democratic support and some Democrats have been emphatic that they don't want to agree to raising budget caps until they have assurances that recipients of DACA, the Deferred Action for Childhood Arrivals program, will be protected. Conservatives in the House are also expected to balk at a deal that raises spending by $300 billion over the next two years. Something will have to give if Ryan is going to get the bill across the finish line.

The House passed a short-term spending bill Tuesday night aimed at keeping the government open. That bill also included a full-year of funding for defense spending. Now that a caps deal has been made, Senate leaders are expected to strip out the full year of funding for defense, attach the caps deal and hope the House can pass their breakthrough bill.

Otherwise, a shutdown looms.

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