How Republican presidential front-runner Donald Trump would pay for his long-proposed (and controversial) 1,100-mile wall along the southwest border of the United States has long been a point of contention for his critics and rivals.

The candidate himself has repeatedly insisted that he would force Mexico to pay for the wall, which would ostensibly crack down on illegal immigration, despite that country’s sovereign leaders (both past and present) vehemently insisting they would do no such thing. While on the campaign trail, Trump has floated the concept of using America’s economic might to pressure Mexico to do his bidding.

According to a new Washington Post report, the economic pressure might come in the form of rescinded money transfers between the U.S. and its southern neighbors. Billions of dollars reportedly flow from immigrants here in the U.S. to their relatives across the border, and Trump has suggested that he’d threaten to cut off those funds, which could potentially have a brutal impact on the already challenged Mexican economy. It is still unclear how or if Trump would have the legal authority to enforce this policy, but it appears to be one of the first examples of policy teeth attached to one his more ambitious proposals.

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The Post learned of Trump’s strategy via a two-page memo, attributed to the candidate himself, which argues that under a provision of the Patriot Act (“know your customer”) the executive branch has the power to regulate these kinds of transactions. The memo, which features Trump’s name and his “Make America Great Again” campaign slogan prominently up top, also predicts that the Mexican government will capitulate within three days once they realize they will be missing out on “$24 billion a year in remittance from Mexican nationals working in the United States.”

“It’s an easy decision for Mexico,” Trump said in the memo, while arguing that “the majority of that amount comes for illegal aliens.”

It is unclear how much of the nearly $25 billion sent by Mexicans living abroad to their homeland actually came from the United States via money transfers, since the total includes international contributions, too. Furthermore, there is no data to determine whether the money is coming from undocumented workers or not. But the Post reports that under the Administrative Procedure Act, Trump could evoke emergency powers by labeling illegal immigration an imminent threat to national security.

In addition to going after fund transfers, the Trump memo also suggested that trade tariffs and the cancellation of visas could also be on the table.

“Immigration is a privilege, not a right. Mexico is totally dependent on the United States as a release valve for its own poverty – our approvals of hundreds of thousands of visas every year is one of our greatest leverage points,” Trump wrote. “We also have leverage through business and tourist visas for important people in the Mexican economy.”

“We have the moral high ground here, and all the leverage,” he added.

Trump has estimated that his proposed border wall could cost anywhere from $4 to $12 billion, and his repeated insistence that Mexico would fund the project has been one of his biggest applause lines on the stump. When Trump first announced his presidential campaign last summer, his anti-illegal immigration stance and wall proposal were the centerpiece of his campaign.

His assertion that Mexico sends criminals and “rapists” across the border into the U.S. angered many civil rights groups and Latino voters, but it also set him apart from the rest of the GOP field. Trump has also gone further than any of his competitors by advocating for the mass deportation of the estimated 11 million undocumented immigrants currently in the United States.

Still, while his positions on immigration have put Trump in the lead of the GOP primary fight is has also put him at a huge deficit with Hispanics, who, according to Gallup figures from last month, disapprove of the Republican candidate by a 77 percent to 12 percent margin.

This article originally appeared on MSNBC.com.