The Democrats have underestimated President Trump yet again. His bilateral immigration deal with Mexico is already proving to be far more effective than his critics had predicted.

With Democrats in Congress still refusing to provide the necessary resources for border security despite the massive surge in illegal immigration that has taken place in recent months, Trump turned to Mexico as an unlikely partner to help get the humanitarian and national security crisis under control.

Predictably, Trump’s critics lambasted the idea from the outset. First, they insisted that his threat to impose across-the-board tariffs on Mexican goods would never lead to an agreement. Then, after Mexico quickly acceded to a deal before the tariffs could take effect, liberals changed course and argued that the actions Mexico had committed to take, such as deploying thousands of their National Guard troops to assist with immigration enforcement and requiring migrants to stay in Mexico while their asylum claims are processed by American authorities, would have no impact on illegal immigration into the U.S.

“I think the president has completely overblown what he purports to have achieved,” Democratic presidential candidate Beto O’Rourke said at the time. “These are agreements that Mexico had already made and, in some cases, months ago.”

Some even argued that the bilateral immigration deal with Mexico was a pipe dream to begin with. They predicted that Trump’s effort to pressure our southern neighbor with tariffs would backfire.

“President Trump has a habit of talking tough and then retreating, because his policies often can’t be implemented or don’t make sense,” Sen. Chuck Schumer said in early June. He was implying that there would be no immigration deal with Mexico because Donald Trump’s tariffs were an empty threat.

After just four weeks, though, we now have concrete proof that Trump knew what he was doing all along. Thanks to Mexico’s deployment of National Guard troops to intercept migrants on their way to the U.S. border, the number of illegal immigrants apprehended at the border declined significantly in June after remaining at abnormally high levels throughout the first half of the year. According to the latest figures from Homeland Security, the number of border apprehensions declined from 132,880 in May to 94,897 in June, a 29% drop in the space of just a few weeks. The improvement was even more dramatic for family units and unaccompanied minors, two categories that have accounted for an unusually large share of the recent flood of illegal immigrants.

Meanwhile, the expanded “Remain in Mexico” policy that was put in place under the agreement is easing the pressure on our immigration enforcement agencies, which have been overwhelmed by the sheer number of people caught illegally crossing the border.

Before Trump negotiated the deal with Mexico, Homeland Security had to release more than 1,200 illegal immigrants into the U.S. interior every single day because Congress had not allocated enough resources to process and care for the huge number of detainees in custody. Now that asylum-seekers have to wait in Mexico until their cases are adjudicated, rather than being released into American communities to await their hearings, fewer than 200 illegal immigrants are being released each day, an 85% decrease.

Of course, when Trump first announced the joint border security agreement with Mexico, his opponents vehemently insisted that the progress he had just achieved was illusory, predicting that the deal wouldn’t actually help to solve the illegal immigration crisis.

That was clearly just wishful thinking on the part of the Democrats, whose ultimate objective is to dismantle our entire immigration system and open our borders to anyone who wishes to enter the country for any reason. After being humiliated by the unexpected ease with which Trump convinced Mexico to help fight illegal immigration, liberals tried to save face by pretending that the deal was toothless. Now they have been humiliated yet again by the undeniable impact the agreement has had in a remarkably short period of time.

In truth, the Democrats have only themselves to blame for underestimating Trump’s border security deal with Mexico. Their radicalism clouded their judgment, just as it has throughout the Trump presidency, and they’ve offered no indication that they’re ready to start accepting reality any time soon.

Jan Brewer, a Republican, served as governor of Arizona from 2009 to 2015.