As thousands of unaccompanied minors have flocked to the United States in recent months, primarily from crime-wracked countries such as Guatemala and Honduras, the Obama administration has been sheltering them in federal facilities around the country while they await processing. U.S. Customs and Border Patrol estimates that more than 52,000 have crossed the border since Oct. 1, double the rate from a year earlier.

President Barack Obama has asked Congress for nearly $4 billion to deal with the crisis, and he’s warned parents in the migrants’ countries that their children may be sent back.

Obama’s approach has fractured Democrats’ political unity on the issue.