Donald Trump has visited the US-Mexico border in an effort to boost his case for a proposed wall after threatening to declare a national emergency over his failure to secure funding.
The president flew south aboard Air Force One to the town of McAllen in Texas on Thursday, some 24 hours after talks with senior Democrats aimed at ending an ongoing government shutdown concluded in acrimony.
Mr Trump denied throwing a "temper tantrum" after House of Representatives speaker Nancy Pelosi and Senate minority leader Chuck Schumer again said they would not fund his wall - a dispute that has seen the government in partial shutdown for 20 days.
On Thursday afternoon the Democrat-controlled House of Representatives passed bills that would re-open agriculture and transportation agencies - though the bills are likely to be vetoed by Mr Trump.
As hundreds of federal workers protested in Washington demanding they be allowed to go back to work, Mr Trump went to a border patrol station as he sought to make his case for why a $5.7bn wall needed to be built.
He told workers there: "It's tough stuff here but it could be a lot easier for you if we had the wall, so we'll get it.
"I think we're winning the battle in a big way."
He repeated his claim that Mexico would end up paying for its construction, albeit via a trade deal rather than a cheque for millions of dollars - something he had promised voters on the campaign trail before the 2016 election.
And after Ms Pelosi told reporters at an earlier news conference in Washington that a wall was "not the best way to protect our borders", the president looked - unconvincingly - to history for evidence of its effectiveness.
"They say a wall is medieval - well so is a wheel, a wheel is older than a wall," he said.
"I looked outside and every single car out there - even the really expensive ones that the secret service use, and believe me they're expensive - they all still have wheels.
"The wheel is older than the wall, you know that? And there are some things that work. You know, a wheel works and a wall works."
Despite his assertion that he was "winning the battle" over the wall, Ms Pelosi and Mr Schumer have continued to insist that the Democrats will not agree to fund it.
But Mr Trump does not appear to be ready to compromise and reopen the government, announcing on Twitter that he was pulling out of a World Economic Forum in Davos, Switzerland, next week because of the shutdown.
Just hours before, he said he would be willing to declare a national emergency.
By law, that could give him authority to use some military money for construction projects for the wall.
As he left the White House for Texas, he said: "I have the absolute right to declare a national emergency. If I have to, I will. I have no doubt about it."
Sky's US correspondent Greg Milam said people in McAllen were more in favour of improving security in other ways.
He explained: "This is the place that has more illegal crossings than anywhere along the US-Mexico border and there are people who live here and understand it very well.
"They say that money would be better spent on improving security and technology at the legal border crossings because that's where they say the drugs and the human trafficking issues that Donald Trump talks about are very real.
"They're not in the unprotected areas of the border.
"But that detail is getting lost in what is very much now about two ideologies. A president who says he wants this wall and won't back down, and the Democrats in Washington who have said a very definite no to that."
Mr Trump can at least look to Montana and South Dakota for some support, with Republican state senators in both suggesting that they contribute to the funding of the wall.
Senator Scott Sales said Montana should give a "small token" of $8m to help build the wall even though the state borders Canada to the north, and the idea was quickly derided by Democrat governor Steve Bullock.
The visit to the border by Mr Trump came as his former lawyer Michael Cohen announced he would testify publicly before a House committee next month.
Mr Cohen - a pivotal figure in investigations by special counsel Robert Mueller into potential collusion between Russia and the Trump election campaign - will testify before the house oversight and reform committee on 7 February.