US President Donald Trump says he is not happy at a deal by congressional negotiators on border security that denied him funds for his promised US-Mexican border wall, but didn't reject it outright as fellow Republicans urged his support.
Trump, who triggered a 35-day closure of about a quarter of the federal government with a December demand for $US 5.7 billion from Congress to help build the wall, said he had yet to decide whether to back the agreement reached by four key Republican and Democratic lawmakers.
"I have to study it. I'm not happy about it," Trump told reporters at the White House.
Funding for the Department of Homeland Security, the Justice Department and a host of other agencies is due to expire on Friday under the stopgap spending measure passed last month by Congress to end the longest federal shutdown in US history.
The deal included border security provisions and money to keep the affected parts of the government funded through September 30, the end of the federal fiscal year.
Congressional Republicans have shown little appetite for another shutdown after taking heavy criticism over the prior one.
"I hope he'll decide to sign it," Senate Majority Leader Mitch McConnell told reporters. House Republican leader Kevin McCarthy also touted the deal.
Trump sent mixed messages about another shutdown.
"I don't think you're going to see a shutdown," Trump said, but he added: "If you did have it, it's the Democrats' fault."
Congressional sources said the agreement included $US1.37 billion for new fencing - about the same as last year - along 90 km of the border but only with currently-used designs such as "steel bollard" fencing. It also addressed capacity at immigration detention facilities, specifically the number of beds for people awaiting possible deportation.
Trump previously threatened to declare a "national emergency" if Congress did not provide money specifically for the wall, an action under which he might redirect other funds already provided by Congress to pay for wall construction.
Fellow Republicans have told Trump such a step would almost certainly prompt a legal challenge.
Trump made the wall a central 2016 campaign promise, calling it necessary to combat illegal immigration and drug trafficking. He said Mexico would pay for it, but Mexican officials rejected that.
McConnell, who had counselled Trump against the previous shutdown, said Democrats had abandoned "unreasonable" demands.
Senior Democrats threw their weight behind the deal and said both sides gave ground. Top Senate Democrat Chuck Schumer said: "I strongly urge the president to sign this."
Trump retreated last month when he agreed to end the shutdown without getting wall money.
The shutdown roiled financial markets and left hundreds of thousands of federal workers and contractors without pay.
Australian Associated Press