President Donald Trump expressed skepticism on Sunday that US lawmakers seeking to avoid another government shutdown could reach a deal on border security that he would accept, as he renewed his vow to build a wall on the southern border with Mexico.

In an interview with the Wall Street Journal, Trump said chances were low that Congress could craft an agreement and avoid another closure of part of the US government in three weeks' time, when funding will expire.

"I personally think it's less than 50-50, but you have a lot of very good people on that board," the president said, referring to the committee of lawmakers appointed to work out a compromise on border security funding.

Another shutdown, Trump told the Wall Street Journal, was "certainly an option."

The president has also said he might declare a national emergency in order to build his border wall. Democrats would likely challenge that in court.

"Does anybody really think I won’t build the WALL? Done more in first two years than any President!" Trump wrote on Twitter on Sunday evening.

Democratic resistance to Republican Trump's demand for $5.7 billion for a border wall resulted in a 35-day shutdown of about a fourth of the US government, a closure that just ended on Friday.

The five-week standoff damaged the US economy, left many federal workers scrambling to make ends meet and tested Americans' patience with delays to air travel, closures of national parks and other disruptions.

After opinion polls showed Americans increasingly blamed Trump for the situation, the president signed a measure on Friday to fund the government for three weeks as congressional negotiators try to work out a bill to fully fund the agencies through September 30.

But Trump also threatened to resume the shutdown on February 15 if he does not get what he wants.

In his interview with the Wall Street Journal, Trump also sounded doubtful about a possible deal involving both wall money and a broader overhaul of US immigration laws.

"I doubt it," he said, when asked if he would agree to citizenship for a group of immigrants known as "Dreamers," who were brought to the United States illegally as children - in exchange for border wall funding.

"That’s a separate subject to be taken up at a separate time," Trump said.

'Shutdowns Not Good Leverage'

Earlier on Sunday, some lawmakers criticised using the closure of federal agencies as a tool in policy disputes. Senior legislators from both parties said the latest shutdown, the 19th since the mid-1970s, was as ineffective as previous ones but much more disruptive as it was the longest in US history.

"Shutdowns are not good leverage in any negotiation," Republican Senator Marco Rubio said on NBC's "Meet the Press," urging congressional negotiators to tackle border security in the three-week talks launched by last week's shutdown-ending deal.

Hakeem Jeffries, chairman of the Democratic caucus in the House of Representatives, said on the same television show that shutdowns were "not legitimate negotiating tactics" in public policy disagreements between two branches of government.

About 800,000 federal workers were furloughed or worked without pay during the shutdown, missing at least two paychecks that officials are now working to make up for.

"We hope that by the end of this week, all the back pay will be made up," acting White House Chief of Staff Mick Mulvaney said on CBS' "Face the Nation."

Federal workers are owed about $6 billion in back pay, according to a study released last week.

As a candidate, Trump pledged to build the wall, with Mexico paying for it. Mexico refused and now Trump wants US taxpayers to pay for the barrier, which he sees as key to curbing illegal immigration and illegal drug flows into the country.

Democrats say a wall would be too costly and ineffective.

It remained unclear when Trump would deliver his State of the Union address, which was postponed during the shutdown. One administration official, who asked not to be named, said on Saturday the speech would likely not occur until February.