U.S. Vice President Mike Pence and other senior Washington officials have met with Democratic congress staff to end a two-week-old partial government shutdown.
President Donald Trump is demanding five billion euros to build a wall along the U.S. border with Mexico, in line with his election campaign promise.
But the Democrats, who are now in control of the House of Representatives, have passed a bill to reopen the government without providing funding for the wall.
Trump reiterated his demand for a border wall in a series of tweets on Saturday.
"The Democrats could solve the Shutdown problem in a very short period of time," Trump said. "All they have to do is approve REAL Border Security (including a Wall), something which everyone, other than drug dealers, human traffickers and criminals, want very badly!"
Trump says he will not sign the bill until he gets the money for the wall.
As both two sides stick to their positions, a quarter of the federal government remains closed and 800,000 public workers unpaid.
Nancy Pelosi, the new Democratic speaker of the House of Representatives, said this week that Trump's proposed wall was "immoral" and a "waste of money."
Trump threatened on Friday to take the step of using emergency powers to build the wall without Congress' approval.
Such a move would almost certainly be met with legal challenges.