US President Donald Trump has insisted that Mexico will still pay for the border wall, claiming he never meant it would make a one-time payment.
“Obviously I never meant Mexico would write a cheque,” Mr Trump said before travelling to McAllen, Texas.
He says Mexico would “indirectly” fund the wall through a revamped trade deal, but a campaign memo shows he planned to compel the country to pay for the wall.
A political row over Mr Trump’s demand has triggered a US government shutdown.
President Trump says he refuses 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.
The funding lapse has dragged into the 20th day, with some 800,000 federal workers expected to miss their first pay cheque on Friday since the partial shutdown began.
Hundreds of federal workers, contractors and supporters rallied outside the White House on Thursday in protest against the shutdown.
“During the campaign, I said Mexico would pay for it,” Mr Trump told reporters on Thursday before travelling to a border patrol station in McAllen, in the Rio Grande Valley of Texas.
“They are paying for it with the incredible deal we made, the USMCA [US Mexico Canada Agreement],” he said.
The deal, which has yet to be ratified by Congress, would replace the 1994 North American Free Trade Agreement (Nafta).
Mexico will be “paying for the wall indirectly, many, many times over,” Mr Trump argued, referring to the pending deal.
Critics say that any savings incurred due to the deal would go directly to private businesses rather than flow into US Treasury.
“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.
But an archived campaign memo from 2016 outlines how he planned to “compel Mexico to make a one-time payment” of $5-10bn (£4bn-£8bn) for the wall.
The president also suggested on Thursday he would declare a national emergency, which would allow him to bypass Congress and open up defence department spending for the physical barrier – a move that would provoke a legal challenge.
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.
How is the shutdown progressing?
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.
The first pay day since the shutdown falls on Friday and will pass without workers getting salaries.
After past shutdowns, workers have generally been refunded with back pay, although that does not apply to those working for third-party contractors. The refunds are also not automatic – Congress must approve the measure.
Some affected federal workers who spoke to the BBC said they had resorted to a number of measures, including taking other jobs, racking up credit card bills, tapping into savings or taking on loans at high interest rates to pay their bills.
Thousands have also applied for unemployment benefits.
The Office of Personnel Management, which oversees federal workers, has urged them to reach out to creditors and landlords for a deferral or reduction of payments.
This weekend the shutdown will become the longest in US history.