The clock is ticking on a potential US government shutdown ahead of Friday's midnight deadline.
A short-term bill to avoid a funding freeze passed the House of Representatives on Thursday, but it faces an uncertain future in the Senate where Republicans only have a razor thin majority.
President Donald Trump has blamed Democrats for the deadlock on Capitol Hill as they seek key concessions on immigration.
"We have a big immigration problem, see what's happening! The democrats want to see a shutdown to get off the subject."
Democrats are threatening not to back the stopgap funding measure unless a deal is reached to protect so-called Dreamers from deportation - young people who entered the US illegally as children.
Last year, Trump ended the Obama-era Deferred Action for Childhood Arrivals (Daca) programme, which protected around 800,000 Dreamers.
The programme is due to end in March and even some senior Republicans say they will not back the short-term funding bill unless a solution over the immigration issue is found.
Republican Senator Lindsey Graham said: "There's a time to fight, and there's a time to deal. It is now time to deal."
Disagreement over immigration, and other budgetary issues, means Friday's deadline is likely to go to the wire.