US President Donald Trump has threatened again to declare a national emergency to fund a border wall without Congress’s approval.
“I have the absolute right to declare a national emergency,” he told reporters.
The White House has denied reports it is looking at diverting funds set aside for reconstruction projects.
A political row over funding the wall has left the US government partially shutdown for 20 days, leaving about 800,000 federal employees without pay.
President Trump has refused to sign legislation to fund and reopen the government if it does not include $5.7bn (£4.5bn) for a physical barrier along the US-Mexico border.
But budget talks have come to a standstill as Democrats – who control the House of Representatives – refuse to give him the money.
Republican leaders insist the party stands behind the president, although some Republican lawmakers have spoken out in favour of ending the shutdown.
On Thursday, Mr Trump visited a border patrol station in McAllen, in the Rio Grande Valley of Texas.
He said that if Congress did not approve funding for the wall, he would “probably… I would almost say definitely” declare a national emergency to bypass lawmakers.
But such a move is likely to face legal challenges.
The money would also have to come from funds allocated by Congress for other purposes – which some Republicans would also oppose.
But one of his supporters, Republican Senator Lindsey Graham, said he could not “see a pathway forward” and urged President Trump to declare a national emergency.
Analysts say such a move would provide political cover to reopen government while allowing Mr Trump to argue he had done all he could to fulfil one of his main campaign promises.
The BBC’s David Willis in Washington says that, with no further talks with the Democrats planned, declaring an emergency now seems the most likely option for the president.
NBC News reported on Thursday that Mr Trump had been briefed on one plan that would involve diverting funding allocated to reconstruction projects in disaster areas , including Puerto Rico, to pay for the wall.
But White House Press Secretary Sarah Sanders later denied the reports. “The NBC story is totally false, fake news, but doesn’t mean the president won’t talk to them at some point,” she said.
Mr Trump spoke at McAllen station, behind a display of weapons and cash said to have been seized by the border patrol.
He was joined by border patrol agents, and relatives of people killed by illegal immigrants.
“If we don’t have a barrier… you’re not going to be able to solve this problem,” he said, adding that people faced “hard work”, “gruelling problems” and “a lot of death” without it.
Mr Trump added: “They say a wall is medieval… There are some things that work.”
Mr Trump made the border wall a key campaign promise – and pledged to make Mexico pay for it.
However, speaking on Thursday, Mr Trump claimed he never meant that Mexico would make a one-time payment.
“When I said Mexico would pay for the wall in front of thousands and thousands of people… obviously I never meant Mexico would write a cheque,” he said.
However, this is contradicted by an archived campaign memo from 2016, where Mr Trump outlined how he planned to “compel Mexico to make a one-time payment” of $5-10bn (£4bn-£8bn) for the wall.
Mr Trump said on Thursday that, instead of a direct payment, Mexico would be “paying for the wall indirectly, many, many times over”, under a new trade deal between the US, Mexico and Canada.
Economists have disputed this and critics say that any savings incurred due to the deal would go directly to private businesses rather than flow into US Treasury.
Partial shutdowns occur when Congress cannot agree a budget by a certain deadline or the president refuses to sign it.
This shutdown, which began on 22 December, has closed 25% of the government. Of the 800,000 federal employees affected, about 350,000 are furloughed – a kind of temporary lay off – and the rest are working without pay.
Shutdown negotiations failed on Wednesday when Mr Trump walked out of a meeting with Democratic leaders.
The president called the meeting “a total waste of time” after top Democrats Nancy Pelosi and Chuck Schumer refused to budge on agreeing to legislation that includes funding for a wall.
The first pay day since the shutdown falls on Friday and will pass without workers getting salaries. They include prison guards, airport security screening staff, and members of the FBI.
This weekend the shutdown will become the longest in US history.