By Steve Holland and Richard Cowan
WASHINGTON, July 8 (Reuters) - The White House asked the U.S. Congress for $3.7 billion in emergency spending on Tuesday to address a cross-border surge of children from Central America that is taxing public resources and causing a political headache for President Barack Obama.
It was Obama's most substantive response to date as he struggles to gain control of a humanitarian crisis along the Texas border with Mexico. The money would both pay to care for the children and accelerate a return to their home countries.
The funding move will test Obama's ability to negotiate effectively with Republican lawmakers who have blocked much of his agenda ahead of a November election when they hope to capture the U.S. Senate.
Obama has vowed to swiftly return to their home countries the tens of thousands of children under 18 who have flocked to the United States in recent months. Many who flee are escaping extreme poverty, gangs and drug violence.
He risks the wrath of Latino allies in the United States who are looking to him to act on his own to loosen, not strengthen, immigration rules.
Seeking to make the request more politically acceptable to lawmakers, the White House added $615 million in urgently needed money to help fight summer wildfires that have been raging in western states.
This brought the total funding request to $4.315 billion, a figure that some Republicans might find difficult to swallow without budget cuts elsewhere.
Due to leave on a Democratic Party fundraising trip to Colorado and Texas, Obama has offered to meet while in Texas with the border state's Republican governor, Rick Perry, who has criticized Obama's refusal to visit the border.
White House officials who briefed reporters said the largest portion, $1.8 billion, would go to the U.S. Health and Human Services Department to provide appropriate care for the children while in U.S. custody.
Without this money, "HHS will be unable to address the influx of children by securing sufficient shelter capacity with the number of children held at Border Patrol stations continuing to increase, for longer periods of time," the White House said.
Another $1.1 billion would go to the U.S. Homeland Security Department to pay for transporting the children, expanding investigations of immigrant smugglers and pay for the detention and removal of undocumented adults traveling with children.
In addition, $433 million would go toward stepping up border enforcement, including an increase in air surveillance. The U.S. Justice Department would receive $64 million to hire about 40 additional immigration judges to reduce the backlog of cases that is slowing the process of deportation.
Finally, $300 million would go to the State Department to pay for repatriating and reintegrating migrants back into their home countries and "help the governments in the region better control their borders," the White House said. (Additional reporting by Mark Felsenthal and Jeff Mason; Editing by Caren Bohan and Howard Goller)