With Donald Trump overruling advisers and betting that riling up his base over illegal immigration at the southern border is the way to go ahead of the 2020 election, Mexico appears ready to hit back by levying tariffs that will hurt swing-state voters — and in turn, hurt Trump.

The president’s latest salvo of tariffs against a crucial trading partner, according to Bloomberg writer Shannon O’Neil, won’t work, mainly because President Andres Manuel Lopez Obrador simply can’t stop the flow of people coming from south of Mexico.

And if the tariffs go into effect, we should expect more South Americans and Mexicans themselves to try and enter the U.S. due to the effect the tariffs will have on the Mexican economy.

Mexico’s response so far has been to try and negotiate, sending a conciliatory letter to Washington D.C. and tweeting platitudes about dignity and respect.

O’Neil, a senior fellow for the Latin America Studies at the Council on Foreign Relations in New York, said that it isn’t just Trump who wants the Mexican government to stop the flow of migrants, but Mexicans themselves who are growing weary of the number of desperate people clogging their roads and communities.

Ultimately, O’Neil says, there’s little Lopez Obrador can do, particularly in the short-term. The Mexican government has upped the number of deportations to more than 50,000 so far this year, passing the 2018 April and May numbers of his hard-line immigration predecessor.

And yet they keep coming.

Per Bloomberg:

Mexico’s immigration bureaucracies are utterly overwhelmed. Its National Migration Institute has never been known for its effectiveness or efficiency, and Lopez Obrador’s misguided budget cuts have exacerbated its failings. And the tiny Mexican Commission for Refugee Assistance, which handles asylum cases, was unable to process even a quarter of the 30,000 applications it received last year. This year, the number is set to double. Money promised by United Nations to open up a new office in Tijuana will help only on the margins.

Mexico could and should spend much more to deal with these human flows. But the United States—whose own interdiction rate was 75 percent in 2016, which meant nearly 200,000 successful illegal entries—is asking a nation with far fewer resources and much less capacity to shoulder a burden that the U.S. admits it can’t handle.

So what’s Mexico to do?

First and foremost, they hope this will all blow over as just an empty threat from Trump, who has threatened to close the border a number of times already.

If Trump insists and goes through with the tariffs, Mexico can respond by hitting the president where it hurts: tariffs on U.S. goods heading south of the border from swing states.

Mexico has done so before, during a trucking conflict and in response to steel and aluminum tariffs. It could impose nearly $20 billion in levies from the get go, raising them each month in tandem with U.S. levels.

This retaliation would highlight the gap between Trump’s anti-Mexican rhetoric and the underlying interdependence of the U.S. and Mexico, with stark consequences for 2020. Many of the biggest exporters to Mexico — Arizona, Michigan, Illinois — are already swing states. New tariffs could throw Texas into recession and put its 38 electoral college votes into play. Trade may indeed decide the next election. But if Trump continues down the same path, not in the way he hopes.

Editor’s note: China has gone a similar route by hurting U.S. farmers with tariffs, forcing the Washington to pay billions in bailouts. Will Mexico have success targeting swing states with tariffs ahead of the 2020 election, hurting Donald Trump? Share your thoughts below.