US President Donald Trump says he is sceptical a deal can be reached on border security before government funding expires again next month.
He spoke to the Wall Street Journal as 800,000 federal employees returned to work after the longest ever closure of federal agencies, lasting 35 days.
The Republican president said he doubts he would lower the sum he is prepared to accept for a US-Mexico border wall.
Congress must agree a new bill by 15 February to avoid another shutdown.
The US economy lost $3bn (£2.2bn) from the closure of federal agencies, according to the non-partisan Congressional Budget Office on Monday.
Its analysis said the economy overall shed about $11bn during the five-week period, but about $8bn would be recouped as employees receive back pay.
A committee of lawmakers from both parties is poised to negotiate, but Mr Trump told the Journal the chances of a political breakthrough are "less than 50-50".
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Asked if he would accept less than the $5.7bn he wants to build a border barrier, he said: "I doubt it."
"I have to do it right," he added, noting that he has not ruled out a second shutdown in as many months to accomplish his signature campaign pledge.
The president also sounded unwilling to make any significant concession to strike a grand bargain with Democrats.
Mr Trump said he doubted he would back citizenship for immigrants who entered the US without documentation as children.
On Friday, the president bowed to mounting pressure to end the crippling shutdown of about a quarter of the US government.
But while Congress quickly passed a bill to fund federal agencies, Mr Trump again came away without a dollar of taxpayers' money for his long-promised border wall.
His perceived retreat provoked a welter of conservative criticism, prompting him unusually to lash out at his favourite cable show, Fox News.
Mr Trump tweeted on Sunday: "Never thought I'd say this but I think @johnrobertsFox and @GillianHTurner @FoxNews have even less understanding of the Wall negotiations than the folks at FAKE NEWS CNN & NBC!"-BBC
