EL PASO, Texas—President Barack Obama on Tuesday tried a new tack on immigration, saying that beefed-up security along the U.S.-Mexico border has proved effective enough that it should draw Republican support for an overhaul of the nation's naturalization system.
Mr. Obama said his administration had met the concerns of Republicans by increasing law-enforcement manpower to record levels and installing new surveillance technology and fencing.
"We have strengthened border security beyond what many believed was possible," he said at the Chamizal National Memorial, as a giant Mexican flag waved across the Rio Grande river.
The president cited several statistics to back up his assertion of tightened borders, including a nearly 40% decrease in arrests at the border, to about 463,000 in 2010. The administration says that is a sign that fewer people are attempting to illegally cross from Mexico.
Mr. Obama didn't mention that deportations hit record levels last year—a trend that has drawn fire from some Hispanic advocates.
The speech was aimed in part at reassuring voters who are worried about border security, and in part at renewing support among Hispanic voters he needs to boost his re-election campaign, particularly in Rocky Mountain states.
He offered no new policy proposals Tuesday, and set no timetable for legislation. Instead, he called for those who support his proposals to build pressure for congressional action from outside Washington.
The president said the new border-control measures will prevent another wave of illegal immigrants from flowing into the country if those already here are allowed to stay.
Some prominent unions including the AFL-CIO have opposed immigration legislation in the past, concerned that new arrivals would pose competition for their members. Senators trying to craft an overhaul have said one of the obstacles has been coming up with a guest-worker program unions and business can support.
Mr. Obama's legislative goals haven't changed since he spoke on immigration last summer, including a path to citizenship for the 10.8 million people already in the U.S. illegally, a program many Republicans oppose as a reward for lawbreaking. Mr. Obama also supports a guest-worker program and making it easier for foreign students educated in the U.S. to stay.
There is virtually no GOP support in Congress for the legislation Mr. Obama wants, though some Republicans have embraced these ideas in the past.
Mr. Obama predicted that no matter what he does, some Republican foes of his approach will demand more. "Maybe they'll need a moat," he said. "Maybe they'll want alligators in the moat."
Arizona Republican Sens. John McCain and Jon Kyl have crafted a $4 billion, 10-point plan that calls for double fencing where there is now single fencing and another 5,000 Border Patrol agents, on top of the 20,700 now in place.
"We hear from our constituents on a daily basis, and, while some progress has been made in some areas, they do not believe the border is secure," Messrs. McCain and Kyl said in a statement Tuesday.
They also pointed to a Government Accountability Office report that found the U.S. has "operational control" of 44% of the Southwest border with Mexico, meaning it has the ability to detect, respond and interdict illegal activity.The administration says that isn't a good measure and officials are working on a better one.
Republicans face pressure within their party to keep the focus on tougher immigration enforcement. But some GOP leaders say the party also needs to improve its standing with Hispanics, the fastest-growing voter group in the U.S.
But the president faces skepticism even from supporters heading into this latest push.
"The moment to use pressure is gone. You missed it. The train left the station," said Rep. Luis Gutierrez (D., Ill.). "I want to be honest with my constituents and with the American people. I don't want to rev them up for something that doesn't have any possibilities of success."
—Miriam Jordan contributed to this article.
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