Trump Warns That Rising Border Crossings May Require an Extra $1.4 Billion

WASHINGTON — The Trump administration has warned Congress that the flow of unaccompanied migrant children at the southern border has increased even further than it anticipated just a few weeks ago and may require an additional $1.4 billion to provide housing and care.

In a letter to congressional leaders dated Friday, the administration said the extra money would be needed on top of $2.9 billion it had already requested to deal with the growing influx of migrant children. The immigration rate has already surpassed the projections used to justify that request, which was sent on May 1.

“Since then, the situation has continued to deteriorate and is exceeding the previous high-end estimate,” Russell T. Vought, the acting director of the White House Office of Management and Budget, wrote in the letter to lawmakers. The rising demands “will exhaust amounts currently available to fund services that involve the safety of human life, protection of property and the immediate welfare of individuals.”

The rising costs underscored that while the president in his public speeches and rallies focuses on the danger of criminals entering the country, the immediate crisis at the border is a humanitarian one — caring for the sick, housing children, holding families in temporary detention facilities and paying for extra asylum screeners.

The government is so overwhelmed that in recent days it began flying hundreds of migrants from South Texas to holding cells in California. Border authorities detained 109,144 migrants at the southwest border in April, including at its legal ports of entry, the highest total since 2007.

The warning about increasing expenditures comes as the administration and Congress struggle to push through an emergency disaster relief spending bill that could be the vehicle for more money for the border situation. President Trump has resisted efforts to provide extra money for Puerto Rico, which is struggling to recover from twin hurricanes in 2017, arguing with inaccurate numbers that it has already gotten enough.

Just a week ago, the House passed legislation providing $19.1 billion in relief for communities hit by various natural disasters and farmers affected by the president’s trade war, with 34 Republicans joining the Democratic majority. Mr. Trump came out against the bill, but Senate Republicans and Democrats have reported progress in recent days toward a compromise.

In a document accompanying Mr. Vought’s letter on Friday, the administration said the number of unaccompanied minors referred to the Department of Health and Human Services for care has increased by more than 57 percent over this time last year. The letter was previously reported by Politico.

The administration has already reallocated nearly $400 million to respond and “curtailed expenditures not essential to the health and safety” of the children. It requested the $2.9 billion previously to increase shelter capacity to 23,600 beds.

If the flow does not significantly exceed the department’s previous worst-case scenario, then the $2.9 billion should be enough, Alex M. Azar II, the secretary of health and human services, wrote in a separate letter accompanying Mr. Vought’s. But he added that he worried the numbers would continue to grow and require even more money.

The $2.9 billion was part of an overall package of $4.5 billion sought by the administration on May 1 for border spending, including expenses for security personnel, additional detention beds, and operations combating human smuggling and trafficking.

While none of that money would go to building Mr. Trump’s border wall, Democrats objected to some planned expenditures like detention beds that they said would enable the president to detain more undocumented immigrants. But they signaled support for the $2.9 billion for care of children.