Donald Trump proposed to block billions of dollars in payments immigrants send back to Mexico if the government there refuses to pay for a border wall, in a potentially devastating move for Mexico's economy.

Trump, who has made building a wall between the U.S. and Mexico to curb illegal immigration a centerpiece of his Republican presidential campaign, released a memo saying he would force Mexico to pay for the wall by threatening to stop remittances until the nation made "a one-time payment of $5-10 billion" to the U.S.

"It's an easy decision for Mexico," Trump said in the memo, which cites a section of the USA Patriot Act antiterrorism law that he argues can be changed to enforce his proposal if he is elected president. The Washington Post first reported his proposal.

It's unclear if Trump would be able to carry out the plan without approval from Congress. Experts interviewed by the Post said that such an interpretation of the rights defined by the Patriot Act would be extremely expansive and likely subject to litigation.

Trump said the majority of remittances Mexico receives are from undocumented immigrants, though the U.S. Government Accountability Office said this year it's difficult to measure that figure.

A Trump campaign spokeswoman did not immediately respond to a request for comment.

World Bank data show Mexico gets about $25 billion in total remittances annually, and while that includes payments originating in other countries, the bulk is from the U.S. The data also show that remittances accounted for about 2 percent of Mexico's gross domestic product in 2014.

Trump has said the U.S.-Mexico border wall would cost between $8 billion and $10 billion to build. Officials in Mexico have repeatedly said they would not fund the border wall as Trump proposes.

Mexican President Enrique Pena Nieto's administration said last year that Trump's plan to bill Mexico for the wall "reflects an enormous ignorance for what Mexico represents, and also the irresponsibility of the candidate who's saying it."

Trump said he would also consider adding trade tariffs to Mexican goods or increasing visa fees for Mexican travelers to increase pressure on the Mexican government to pay for the wall.

"Mexico needs access to our markets much more than the reverse, so we have all the leverage," Trump said in the memo, which also proposes canceling or denying business or tourism visas for some "important people in the Mexican economy."

"It would have an effect on Western Union and MoneyGram revenue if this happened," said Larry Berlin, an analyst at First Analysis Corp. who covers those companies. "But to get there, Donald Trump has to win the Republican nomination, he has to win the White House, he has to be able do this, and God knows whether he can do it legally or not. So there are all kinds of obstacles before this could ever really matter. I don't think they're quaking in their boots quite yet."

Colorado- and Texas-based spokesmen for Western Union Co. and MoneyGram International Inc., two companies that offer money transfer services, couldn't immediately be reached.

Trump released his proposal as Republican voters went to the polls in the Wisconsin primary. If Trump loses that contest Tuesday to Texas Senator Ted Cruz, as polls indicate is likely, it would complicate his path to winning the nomination outright before the party's national convention in July.

Trump's call for a wall stretching hundreds of miles across the southern border of the U.S. has sparked international outrage, even as many of his Republican rivals embraced the idea.

Pope Francis even weighed in, saying in February that Trump "is not Christian" if he focuses on building walls, rather than bridges.

Former Mexican President Vicente Fox used an expletive to describe the wall when he said that Mexico would not pay for it.

"He should pay for it," Fox told Fusion in February. "He's got the money."

The wall proposal — and the plan to use economic leverage to get Mexico to fund it — reflect broader pieces of Trump's foreign and domestic policy vision.

Trump has proposed to deport all undocumented immigrants, sending as many as 11 million people out of the U.S. He has also threatened to use tariffs and taxes to punish countries that trade with the U.S., including China, Japan and Vietnam.

As those proposals have drawn rebuke from politicians and business leaders on both sides of the political spectrum, Trump has continued to dominate the Republican presidential primary.

Trump said Tuesday he has been endorsed by the National Border Patrol Council, a union for border patrol agents.

"The border patrol — 15,500 people, 15,500 people — and they've never done it, they endorsed me for president," Trump said Tuesday on Fox News. "I didn't ask them for it, they just came out of nowhere and endorsed me."

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