President Donald Trump has once again backed off claims that Mexico will pay for a wall along the US-Mexico border.

This seems to fly in the face of Trump's campaign promise that Mexico would pay for such a wall.

On Thursday, Trump said he "never meant they're going to write out a check" for the wall.

During the campaign, however, the Trump team released a proposal designed to force Mexico to make a down payment on a wall.

Trump now says Mexico will pay "indirectly" via updates to the NAFTA trade deal. Experts say that doesn't make sense either.

President Donald Trump has backed further away from his long-held promise to make Mexico pay for a wall along the US's southern border.

During a question-and-answer session with reporters before heading to McAllen, Texas, on Thursday, Trump claimed he never meant Mexico would pay for the wall directly.

"When, during the campaign, I would say Mexico is going to pay for it, obviously I never said this and I never meant they're going to write out a check," Trump said. "I said they were going to pay for it — they are. They're paying for it with the incredible deal we made called the United States-Mexico-Canada, USMCA deal."

But as far back as Trump's presidential announcement, the president made it clear that Mexico would be funding such a wall.

"I will build a great, great wall on our southern border, and I'll have Mexico pay for that wall," Trump said in June 2015.

Additionally, the Trump campaign released a plan designed to coerce Mexico to make a direct payment of $5 billion to $10 billion that would go toward the wall.

"It's an easy decision for Mexico: Make a one-time payment of $5-10 billion to ensure that $24 billion continues to flow into their country year after year," a plan from the campaign says.

Later, Trump began to say Congress would appropriate funds for the wall and then Mexico would pay that money back at a later date.

"The dishonest media does not report that any money spent on building the Great Wall (for sake of speed), will be paid back by Mexico later!" Trump tweeted in January 2017.

But now Trump no longer argues that to be the case. Perhaps recognizing that Mexico is almost certain never to pay directly for the border wall, Trump seems to be testing arguments that Mexico will pay for the border wall indirectly.

The latest of Trump's suggestions is that the newly updated North American Free Trade Agreement with Canada and Mexico, now known as the USMCA, will pay for the wall. But economists and trade experts say that claim doesn't stand up to scrutiny, because the new agreement is a minor update to the existing trade deal and isn't expected to create a substantial amount of economic growth.

Read more: Trump says Mexico will pay for the border wall 'indirectly by the great new trade deal.' That's just not how it works.

Additionally, in that scenario, the money would still come from the American public's taxes rather than Mexico.