President Donald Trump said Monday on Fox News that he planned to put any members of the migrant caravan who apply for asylum into new “tent cities” that would be “all over the place,” sharpening his recent efforts to politicize the southern border ahead of next month’s midterm elections.

“We’re catching; we’re not releasing,” Trump said in the interview with Fox News host Laura Ingraham. “So if they want to come over, we’re not even doing that. We’re not letting them into this country. If they apply for asylum, we’re going to hold them until such time as their trial takes place.”

The president said he would order the construction of tent cities that’d be “very nice.” But he said he wouldn’t spend “hundreds of millions of dollars” on “structures” to house anyone detained while awaiting the outcome of an asylum application.

“We’re going to put tents up all over the place,” Trump said, before noting that “they’re going to wait, and, if they don’t get asylum, they’re going to get out.”

.@POTUS on facilities for asylum seekers: "We’re going to build tent cities. We’re going to put tents up all over the place." @IngrahamAngle pic.twitter.com/fL3ALkNbz4 — Fox News (@FoxNews) October 30, 2018

His comments come amid nationwide attention over a 3,500-member migrant caravan that has traveled through Central America and into Mexico on its way to the U.S. border, where many people traveling in the group plan to apply for asylum after fleeing violence in Honduras. Trump said Monday he planned to deploy 5,200 troops to the region by the end of the week, even though the caravan itself, in which people are traveling mostly on foot, is weeks away from the border.

Critics have accused the White House of using the U.S. military to rally voters ahead of the midterms, especially since Republicans face a tough battle to retain control of the House of Representatives.

Clara Long, a senior researcher for the U.S. Program at Human Rights Watch, said the proposal sounded like a “very expensive disaster” in the making.

“Having manufactured a crisis around the caravan, Trump is now explicitly vowing to waste millions of dollars of taxpayer money on it. When it comes to children, immigration detention is never appropriate under human rights law,” Long said in an email to HuffPost. “The detention of asylum seekers should be avoided apart from short periods necessary for screening.”

Trump on Monday once again made baseless claims to Ingraham that many in the caravan were “bad people,” some of whom he said were “in gangs.” He’s repeated such refrains at campaign rallies in recent weeks, attacking his Democratic opponents as the “party of crime” and of open borders.

It’s unclear if his recent tent city proposal would be legal, and such a plan would likely provoke a fierce court battle.

In July, a federal judge barred the Trump administration from issuing blanket detention of asylum seekers and ordered they be freed while their applications were pending as long as individuals weren’t a flight risk or didn’t pose a threat to national security.

It’s becoming increasingly harder to be granted asylum in the United States, according to new Department of Justice figures released Friday. The agency is approving asylum cases at the lowest rate in almost two decades as the White House has moved to roll back the circumstances under which foreign citizens are able to apply for such protections, an analysis by BuzzFeed News found.

The Migration Policy Institute found just 33 percent of asylum applications had been approved in the 2018 fiscal year, down from an average of 44 percent to 55 percent under President Barack Obama. The last time the approval rate slipped that low was 1999.

The number of applications has increased dramatically, however, and more than 14,000 people were granted protection in the 2018 fiscal year.