WASHINGTON (AP) — Tens of thousands of children streaming from chaotic Central American nations to the U.S. border have overwhelmed the government’s ability to respond, senior Obama administration officials testified Wednesday as they urged senators to agree to the president’s emergency spending request for the crisis.

But as President Barack Obama traveled to Texas, Republican opposition hardened to his $3.7 billion request, leaving any solution unclear. At the same time, the political pressures on the president appeared to grow from all sides, as Republicans denounced him on the Senate floor, and even some Democrats began to join GOP demands for him to visit the U.S.-Mexican border — calls the White House continued to reject.