WASHINGTON — US congressional leaders said on Tuesday they were close to clinching an elusive budget deal that would keep government open -- despite President Donald Trump calling for a shutdown if he does not get his way on immigration.

The Senate’s top Republican and Democrat signaled a deal was imminent that would raise both defence and non-defence spending maximum levels for the next two years, beyond the limits imposed by a 2011 law, clearing the way for lawmakers to swiftly pass a temporary spending bill before the government runs out of money at midnight Thursday.

Democratic Senator Chuck Schumer said there was "real progress" on a budget deal, while Senate Majority Leader Mitch McConnell said "we’re on our way to getting an agreement, and getting it very soon".

The bipartisan breakthrough came as the Republican-controlled House of Representatives debated and then passed a controversial six-week stopgap spending measure.

Schumer and Democrats threatened to block the bill in the Senate because it funds the military, but not domestic programmes, through the remainder of the fiscal year.

"We support an increase in funding for our military and our middle class," Schumer insisted. "We don’t want to do just one and leave the other behind."

But Schumer said that the long-term deal being finalised would essentially make that concern moot, allowing his caucus to support a temporary funding measure that includes the language about spending levels through 2019.

Running in tandem with the shutdown showdown is a bitter fight over immigration, and lawmakers were sounding increasingly pessimistic about the prospects of reaching consensus on a plan that shields 1.8 million undocumented migrants from deportation.

’Shut it down’

Democrats have bridled at Trump’s proposal, which puts those immigrants on a pathway to citizenship but imposes dramatic curbs on legal immigration including ending the green card visa lottery and restricting family reunification visas.

Last September Trump scrapped the Obama-era programme known as Deferred Action for Childhood Arrivals (DACA), meaning the 690,000 so-called "Dreamer" immigrants under its protection could face deportation as early as March 5 if Congress fails to act.

Democrats have pushed hard to tie immigration to the funding fight, and Republicans blamed the opposition party for triggering a three-day government shutdown over the issue last month.

Trump appeared to lose patience over a Congress still deadlocked on immigration.

"I’d love to see a shutdown if we can’t get this stuff taken care of," he said at the White House.

"If we have to shut it down because the Democrats don’t want safety... let’s shut it down."

Since coming to office, Trump has repeatedly tried to link migration with crime. On Tuesday he held a roundtable discussion with lawmakers and law enforcement officials where he lamented that "killers" were coming across the border and living illegally in the United States.

Hours earlier on Twitter, the president blasted Democrats for their opposition to what he called a "merit-based" immigration system.

"If D’s oppose this deal, they aren’t serious about DACA-they just want open borders," he wrote. — AFP