US president Donald Trump appeared to undermine his own party's efforts to avoid a government shutdown that could kick in at midnight on Friday in a series of ill-tempered tweets on the eve of the deadline.
Mr Trump said on Twitter that he believed a child healthcare programme – which Republicans had included in their stopgap proposal – should not be included in the plan.
“CHIP should be part of a long term solution, not a 30 Day, or short term, extension!” he said, referring to the Children’s Health Insurance Programme.
Republicans had included a six-month extension of the programme in their proposal, in a bid to lure some Democrats to support the Bill.
Mr Trump's interjection appeared to complicate efforts to secure a deal, which Congress had hoped to put to a vote on Thursday.
With federal funding expiring at midnight on Friday, Congress was facing a growing possibility of a government shutdown.
In particular, there were growing concerns that the Bill might not pass the senate where Republicans have a small majority, with several Republicans outlining their opposition to a short-term solution.
While some conservative Republicans are frustrated that a failure to agree a longer-term budget plan defers again an increase in funding for the military, others want their immigration concerns to be included in the Bill.
This is the fourth short-term funding measure proposed by Congress amid failures to agree a longer-term budgetary plan. The last government shutdown occurred in 2013 during Barack Obama’s presidency and led to the closure of national parks and government offices.
The latest talks have been beset by disagreements over immigration, with Democrats calling for a solution for so-called “dreamers” – young immigrants who arrived in the US as children – to be included in the deal. Mr Trump has insisted that funding for his proposed wall along the US-Mexican border also be included.
Mr Trump, who travelled to a small factory in Pittsburgh on Thursday to celebrate what the White House termed his "pro-job, low-tax" agenda, also reiterated his support for the border wall in a series of tweets on Thursday.
Following a suggestion by White House chief of staff John Kelly that the president's thinking had evolved on the issue, Mr Trump insisted that his view on building a wall along America's southern border had not changed.
Mr Kelly told a group of Hispanic members of Congress on Wednesday that Mr Trump had not been fully informed when he promised voters a wall last year, according to reports.
He repeated the view in an interview on Fox News, saying that Mr Trump’s views on the wall had evolved. “Campaigning and governing are two different things, and this president has been very, very flexible in terms of what is within the realm of the possible.”
But Mr Trump directly contradicted his chief of staff in a flurry of early-morning tweets.
“The Wall is the Wall, it has never changed or evolved from the first day I conceived of it,” the president tweeted, adding that it was never intended to be built in areas with natural protection such as mountains, wastelands or rivers.
He added: "The Wall will be paid for, directly or indirectly, or through longer term reimbursement, by Mexico, which has a ridiculous $71 billion dollar trade surplus with the U.S. The $20 billion dollar Wall is "peanuts" compared to what Mexico makes from the U.S. NAFTA is a bad joke!."
Later, Mr Trump said that Mr Kelly was doing a “terrific job” and is a “really special person”.
Mr Kelly, a retired four-star general, was appointed to the White House last summer. His arrival coincided with the departure of senior officials including Reince Priebus, Steve Bannon and Sean Spicer.