Congressional leaders seemed optimistic that lawmakers would be able to pass a long-term federal spending bill and year-end tax this week in order to avert a government shutdown.

Republicans and Democrats spent the weekend and Monday night working to complete the $1.1 trillion spending bill for fiscal year 2016, in addition to a package that grants up to $750 billion in tax breaks for businesses and low-income workers.

Multiple congressional aides said they believed the text of the spending bill could be ready by Tuesday. However, it not clear whether or not the legislation would be completed in time to vote on it before the deadline, which is 12:01 a.m. Thursday, reports The Wall Street Journal. If they miss the deadline, then the stopgap funding would need to be extended.

Republicans and Democrats are at odds over the policy provisions that GOP lawmakers want to attach to the bill, despite President Barack Obama's promise to veto a bill that includes certain amendments. One of the measures Republicans are pushing for is a block on Obama's environmental regulations and the implementation of the Department of Labor new rules for financial advisers who manage retirement funds.

Nonetheless, Senate Majority Leader Mitch McConnell said lawmakers "made a lot of progress in recent days."

While addressing the Senate floor on Monday, he added that the negotiations were not quite done.

"We'll continue to consult and engage with colleagues as we make further progress on these last two significant items we must complete this year," McConnell said, according to the New York Times.

Likewise, House Speaker Paul Ryan told House Republicans Monday night he expected both the spending and tax bills would be completed Tuesday. As a result, this would give way for votes in the House on Thursday, said Republican Rep. Dennis Ross.

The Senate Democratic leader, Harry Reid also reassured the public that lawmakers are working on passing a bill.

"Everybody is working hard toward a bipartisan compromise on the omnibus and the so-called tax extenders legislation," Reid said on the Senate floor. "We're not there yet. Keeping the federal government open and funded is a congressional responsibility. I am confident we will fulfill that most basic constitutional duty."