World Bulletin / News Desk
Lawmakers had until midnight to come to terms on a budget deal, but Senator Rand Paul filibustered proceedings in protest over a proposed spending bill's increases to the federal deficit.
"A country cannot go on forever spending money this way," Paul said on the Senate floor. "What you're seeing is recklessness trying to be passed off as bipartisanship."
The budget deal had gained traction in both chambers heading into Thursday night with expectation growing that it would easily pass in the Senate.
The legislation would increase defense spending by $165 billion and domestic spending by $131 billion over the next two years, as well as suspend the debt limit for one year. It also would have boosted disaster aid funding by about $90 billion.
But with Paul's filibuster successfully derailing efforts, lawmakers are scrambling early Friday morning to move towards a new vote.
The Senate is expected to vote around 1 a.m. (0600 GMT), with a House vote expected sometime later.
Passage is all but assured in the Senate, but House leadership faces a difficult road in moving the budget bill through the chamber. An unlikely alliance of far-right Republicans and immigration-centric Democrats are opposing the measure, complicating House Speaker Paul Ryan's early morning agenda.
If votes do send the bipartisan spending bill to President Donald Trump's desk in the early morning hours, and it is quickly signed, government operations are unlikely to lapse.
However long the shutdown lasts, this is the second such funding crisis in less than a month after Democrats derailed a previous spending bill over a lack of protections for immigrants brought to the U.S. illegally as children.
The immigrant group, collectively known as "Dreamers", have been a central focus for Democrats after Trump ended the Obama-era DACA program last year, giving lawmakers until March to come up with a solution for hundreds of thousands of people he put into legal limbo.