Former Texas Rep. Beto O'Rourke, a Democratic candidate for president, denounced the Trump administration's controversial "Remain in Mexico" policy for asylum seekers, accusing the U.S. government of forcing desperate migrants into precarious situations in Mexico.

"This inhumane policy is causing suffering and death," O'Rourke said on "Face the Nation" Sunday.

Under the policy, officially called the Migrant Protection Protocols (MPP) by the administration, migrants who claim asylum at certain ports of entry along the southwestern border are required to wait in Mexico while their cases are adjudicated in the U.S. Although it's currently in place in San Diego, Calexico and El Paso, the administration has vowed to expand the program, which is being challenged in court, along the entire southern border.

The White House is betting on the policy, which has now returned more than 15,000 asylum seekers to Mexico, to curb large-scale migration from Central America. But immigrant advocates, lawyers and even some current asylum officers overseeing the program have said the practice violates U.S. and international refugee law because it sends back asylum seekers to places where they may face persecution.

These places include the Mexican border cities of Tijuana, Mexicali and Ciudad Juárez, which borders El Paso, the city O'Rourke represented in Congress.

"Through a program that effectively shuts them out of this country and our laws, [migrants] are forced to stay in Ciudad Juárez, where they are prey to criminal organizations, where they are penniless and where they are suffering, and where too many feel like they are forced to try to cross in between our ports of entry," O'Rourke said.

The former Texas congressman is set to visit Ciudad Juárez later on Sunday to meet with migrants returned under the "Remain in Mexico" policy. Since the Trump administration began turning back asylum seekers at the El Paso port of entry, thousands of migrants have been stranded in Ciudad Juárez, one of the most violent cities in the Western Hemisphere, looking for shelter, employment and legal representation while they await their day in court in the U.S.

O'Rourke said he's hoping his visit to the Mexican border city will shine a spotlight on one of the Trump administration's lesser-known immigration policies and its impact of thousands of migrants.

"Going to Ciudad Juárez, Mexico and meeting with these asylum seekers is a great way for the American public to know what is being done in our name right now," he said.