After almost a year of keeping us guessing, Republican hopeful Donald Trump has finally revealed how he plans to get Mexico to pay for the wall along the U.S.-Mexican border that he says he would build as president. And his idea couldn’t be more counterproductive.

In a two-page memo to The Washington Post to clarify how he would pay for his proposed 1,000-mile border fence, Trump said that he would threaten Mexico with cutting part of the estimated $25 billion in remittances that Mexicans living in the United States send their families back home unless Mexico pays for the wall.

If Mexico fails to make “a one-time payment of $5-10 billion” to pay for the border wall, the United States would expand the Patriot Act antiterrorism law to cut off part of U.S.-based Mexicans’ family remittances to their home country, he said. He added, characteristically, “It’s an easy decision for Mexico.”

Manuel Orozco, a migration expert with the Inter-American Dialogue think tank in Washington, D.C., who has done several studies on family remittances, says Trump’s proposal to cut these flows is “deranged,” among other things because the U.S. president would have no authority to do such a thing. It would take congressional action, he said.

More importantly, the measure would backfire, because it would cripple Mexico’s economy and drive more Mexicans to move to the United States.

“The immediate effect would be to increase migration,” Orozco told me. “You would be financially strangling millions of Mexican people, depriving them of about half of their monthly income. That would drive many of them to seek a better life in the United States.”

Cutting family remittances would create havoc in the Mexican economy, because these monthly flows amount to more than Mexico’s tourism income, and — more importantly — it’s money that goes directly into the pockets of Mexico’s poorest.

About 6 million of Mexico’s estimated 28 million families receive family remittances. In some poverty-ridden states, such as Oaxaca and Chiapas, many families depend on these money transfers for their livelihood. Take that money away, and they will have little option but to emigrate, most often without papers.

Trump would reply that his proposed “beautiful” wall would prevent Mexicans from crossing the border illegally.

But more than 40 percent of undocumented migrants are not entering the country through the land border, but flying into U.S. airports. They come in with tourist visas and overstay, U.S. officials say. Trump’s proposed wall would do nothing to stop those migrants.

In addition, cutting family remittances would drive more Mexican youths into crime, which would drive many more Mexicans to migrate. An even more crime-ridden or socially unstable Mexico would hardly be good for the United States, migration experts argue.

My opinion: Trump’s proposal is not only inhumane, but counterproductive. As Orozco said, it would only help increase the flow of undocumented Mexicans to the United States at a time when illegal immigration is way below what it was in 2008.

It’s typical of Trump’s simplistic proposals, like his vow to deport 11 million undocumented U.S. residents, build a wall along the border, or pull out of NATO, which would do more harm than good.

Unfortunately, after Trump’s defeat in Tuesday’s Wisconsin primary, I’m afraid he will only step up his populist xenophobic proposals in coming weeks to keep making headlines and draw more extreme-right voters to the polls. He is ahead in the polls in several upcoming primaries, including New York’s, and must win them decisively to maintain a decent chance to win the Republican nomination.

Trump has said that his family is urging him to be more “presidential,” but I’m afraid he will stress his crazy proposals in coming weeks, and probably come up with new ones. His latest plan to cut family remittances may just be a sample of this.

— Andres Oppenheimer is a Latin America correspondent for the Miami Herald.