By David Lawder

WASHINGTON (Reuters) - The Obama administration's $3.7 billion request for emergency funds to bolster U.S. border security and deal with a massive influx of migrant children from Central America is too high and will be reduced, an influential Republican lawmaker said on Friday.

House of Representatives Appropriations Committee Chairman Harold Rogers said the amount was "too much money" and a large portion of the funds needed to deal with the problems could be handled through the normal spending bills for the 2015 fiscal year starting on Oct. 1.

He declined to say what he believed was a more appropriate amount and said the committee will produce an estimate soon.

"We're crunching the numbers carefully, I'll hopefully be able to give you a better answer next week," Rogers said.

The $3.7 billion in emergency funds would help pay for temporary detention centers, increased border security and additional immigration court judges to process asylum cases more quickly. Obama administration officials warned lawmakers on Thursday that border security agencies would run out of money this summer if the request was not approved.

Republican U.S. House Speaker John Boehner has said he will wait for recommendations from Rogers before making any decisions about the request.

If these costs are handled through the appropriations bill that funds the Department of Homeland Security, they would be subject to an overall $1.014 trillion cap on discretionary spending, meaning that there would have to be cuts elsewhere.

Emergency appropriations measures, typically for wars or natural disaster relief, do not require offsets and simply add to federal deficits.

The Obama administration also wants to change a 2008 anti-trafficking law requiring deportation proceedings for children that arrive from countries that do not share a border with the United States. This would allow authorities to quickly deport newly arrived children from Central American countries, as they currently are able to do with children arriving from Mexico or Canada.

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Rogers said such a change could be handled directly in legislation that contains the approval of emergency funds, adding that the legislation would be approved before a five-week congressional recess that starts on Aug. 1.

"There are immediate needs and emergencies, and that's what we're trying to put together right now. And a lot of what could be spent is contingent on whether we change the '08 law," Rogers said.

He added that the House's emergency spending legislation will contain "substantial border security measures, monies that I think should be accepted well in our House and I would hope, the White House."

(Editing by Doina Chiacu)