Wednesday's Senate and House votes seek to ensure the $1 trillion U.S. budget bill passes both chambers and is sent to President Obama this week, aides said.
Senate Majority Leader Harry Reid, D-Nev., set an early afternoon vote on a stopgap spending bill known as a continuing resolution that will keep the government operating through Saturday, giving lawmakers three days to pass the trillion-dollar, 8-1/2 month federal budget.
The Republican-led House approved the continuing resolution on a voice vote Tuesday.
The joint measure is needed because the government is set to run out of money at midnight Wednesday.
Lawmakers didn't pass a 2014 budget bill by Sept. 30, 2013, the end of the government's last fiscal year. They instead passed a continuing resolution that provided bridge funding to government agencies through Wednesday.
Assuming the Senate passes the resolution, Obama is expected to sign it into law within hours, before current funding expires.
While the Senate votes on the emergency stopgap measure, the House is expected to vote on the trillion-dollar omnibus bill -- which is actually 12 bills in one, totaling 1,582 pages.
"I feel really good," Rep. Tom Cole, R-Okla., was quoted by Politico as saying.
"I think we'll get a majority of the majority. I expect that on both sides of the aisle," the fourth-ranking House Republican leader said.
If the House passes the omnibus Wednesday, Reid could call up the bill the same day, Politico said.
The Senate is expected to debate the phonebook-size bill until Thursday or Friday, aides said.
"If the House comes with a big vote, we'll get a big vote too," said Sen. Richard Shelby of Alabama, the top Republican on the Senate Appropriations Committee.
"It's not everything anybody wanted, but we've been working hard at it and it will lead us, hopefully, to regular order," he said in remarks quoted by Politico.
House and Senate leaders said they intended to make sure the compromise budget is passed and sent to Obama by the Saturday deadline.
At the White House, Obama expressed support for the bill and urged lawmakers to "pass that funding measure as quickly as possible so that all these agencies have some certainty around their budgets."
The measure, which would keep the government running through Sept. 30, provides $1.012 trillion in discretionary spending for defense and domestic programs -- up from $986 billion last fiscal year.
It also includes $92 billion for emergency overseas funding for foreign refugee assistance, the war in Afghanistan and other operations, the Wall Street Journal said.
The measure reverses some cuts to military veterans' pensions that were included in a broader budget agreement last month and defeats Republican efforts to strip financing to carry out the Affordable Care Act.
But the healthcare law, commonly known as "Obamacare," will be funded sparingly -- keeping money for the agency implementing the law at last-year levels and cutting $1 billion from a public-health fund Republicans said they feared the White House would use to bolster the law's online insurance exchanges.
No money is budgeted for some administration priorities conservatives opposed, such as construction of high-speed rail and a preschool development grants program.
On the other side, new regulations supported by liberals are blocked, including a standard for energy-efficient light bulbs and livestock and poultry controls.