By Doina Chiacu and Richard Cowan
WASHINGTON (Reuters) - U.S. border security will probably suffer if Congress fails to act on President Barack Obama's $3.7 billion request to cope with the explosion of child migrants into the U.S. Southwest, lawmakers and congressional aides warned on Tuesday.
Those concerns came amid signs that a Republican bill in the House of Representatives and a Democratic measure in the Senate, both of which were more modest than Obama's request, faced challenges.
The Democratic-controlled Senate has scheduled a procedural vote for Wednesday on a $2.7 billion border funding bill. Senator John Cornyn of Texas told reporters he did not know of any fellow Republicans who will support it, indicating it likely will fall short of the 60 votes needed to advance in the 100-member Senate.
Senator Ted Cruz of Texas, who is influential with House Republicans, called the House bill "disappointing," complaining it failed to overturn Obama's 2012 decision to suspend deportations for some undocumented residents who were brought into the United States illegally by their parents.
In even stronger language, Republican Senator Jeff Sessions of Alabama said the House bill was "unworthy of support" and represented a "surrender to a lawless president."
With no compromise in sight, it appeared that Congress could embark on a five-week summer recess on Friday without signing off on any additional funds for the border crisis.
The Immigration and Customs Enforcement agency is on pace to run out of money in mid-August, and U.S. Customs and Border Protection in mid-September, Homeland Security Secretary Jeh Johnson has said.
If extra funding is not provided, the government will have to transfer money from other agencies to deal with the crisis at the border, where 57,000 children traveling alone have tried to enter the United States from Central America this year.
The transfer of funds is known as "reprogramming" and can be carried out by the Obama administration without legislation.
Senate Homeland Security Committee Chairman Tom Carper, a Delaware Democrat, was "deeply concerned" that forcing the Department of Homeland Security to move money around will affect other critical operations, according to a Democratic committee aide.
Border security will be hurt because the department probably would need to reduce aerial support for the Border Patrol and put off buying technology needed at border points, according to Democratic and Republican congressional aides.
"We also understand that it would hinder some of the very functions critics of the supplemental (funding) seem to support: expedited detentions and deportations of undocumented migrants," the Democratic aide said on condition of anonymity.
House Homeland Security Committee Chairman Michael McCaul, a Texas Republican, said he understood that reprogramming would take money from the Coast Guard and cybersecurity, "and so I am very disturbed at the administration's reprogramming approach."
McCaul said he was meeting with Johnson on the issue later on Tuesday. He said House Republicans want him to take money out of Federal Emergency Management Agency operations instead of border security.
The House bill would provide $659 million through the end of the fiscal year, Sept. 30, which is also sharply lower than the $2.7 billion the Senate wants.
But a bigger sticking point will be House Republicans' proposed changes to a 2008 human trafficking law to allow quicker deportation of children from Honduras, Guatemala and El Salvador, something the Democratic-controlled Senate is unlikely to agree to.
(Additional reporting by David Lawder and Emily Stephenson; Editing by Jonathan Oatis and Mohammad Zargham)