Homeland Security Secretary Janet Napolitano vehemently defended a proposed overhaul of the national immigration system, in spite of opponents citing national security concerns to slow down the bill in the wake of the Boston Marathon bombings.

In fact, she insisted new legislation would in fact boost national security.

While testifying at a Senate Judiciary Committee hearing on Tuesday, Napolitano said sweeping immigration legislation would improve U.S. security by helping authorities to know who is in the country.

Pointing out that the wide-ranging bill circulating in Congress devotes more money to securing the border, Napolitano said the eventual path to citizenship for the 11 million immigrants here illegally is of great importance.

Republicans have criticized such a path as a divisive proposal that rewards law-breakers. But Napolitano said it is a fundamental tool to help law enforcement authorities know who is here and something that might have helped flag when one of the suspected Boston bombers traveled to Russia last year.

"One of the real significant improvements made by this bill is to bring people out of the shadows," she said. "We know who they are. We know where they are. And by the way, from a police perspective, once these people know that every time they interact with law enforcement they won't be subject to removal, it will help with the reporting of crimes, the willingness to be a witness and so forth."

Napolitano's support for legislation that's a top second-term priority for President Barack Obama was no surprise. While in the past she has criticized the idea of making a path to citizenship conditional on accomplishing border security goals first — as the new bill does — Napolitano didn't repeat that criticism Tuesday. Instead, she said the border security "triggers" in the bill are achievable, suggesting they wouldn't loom as major impediments to citizenship.

Napolitano's testimony came as last week's Boston Marathon bombings have clouded the introduction of the landmark immigration legislation, with Republicans suggesting it should be slowed down or revisited until more is known about any loopholes in the immigration system that the Boston bombers may have exploited, or national security flaws that should be addressed in the bill.

An author of the bill, Sen. Lindsey Graham, R-S.C., was considering an amendment to require tougher background checks for certain immigrants deemed to pose a higher risk, such as those seeking asylum, an aide said late Tuesday.

But so far there's no indication the two suspected bombers, brothers of Chechen origin, violated U.S. immigration laws. They came legally about a decade ago when their family sought asylum, and both became legal permanent residents while one eventually attained U.S. citizenship.

Napolitano defended the asylum system now in place, describing an extensive process with multiple screenings. Napolitano also said the process has improved in the past four years, and she said the new immigration bill would build on that.

But the top committee Republican, Sen. Chuck Grassley, R-Iowa, raised concerns because the bill eliminates a requirement that people apply for asylum within a year of arriving in the country, and allows new applications from those whose cases have been unsuccessful because they didn't comply with the one-year bar to reapply. Napolitano said that nothing in the bill would weaken asylum procedures.

Authors of the bill, including Sen. Chuck Schumer, D-N.Y., have said they're open to changes in the legislation should any issues come to light in the wake of the Boston situation.

So far, though, there have been no obvious flaws exposed in the immigration system by the Boston events that aren't already addressed in the bill. The FBI apparently missed a trip to Russia by one of the suspected Boston bombers last year because his name was misspelled on a travel document, but that would be fixed in the bill because passports would be swiped electronically, not entered manually as now happens, Schumer said.

Napolitano disclosed Tuesday that despite the misspelling, the Homeland Security Department had known of the Russia trip because of "redundancies" in the system, but she praised the new electronic entry-exist system proposed in the bill. "It really does a good job of getting human error, to the extent it exists, out of the process," she said.

Schumer and three other authors of the immigration bill sit on the Judiciary Committee, and they repeatedly elicited Napolitano's praise for security enhancements in the bill. She found less to agree on with some Republicans on the panel, who questioned her claims that border security had already been improved under the Obama administration and that the bill would do even more.

"I'm concerned that the bill we're discussing repeats the mistakes of the past and won't secure the border and stop the flow of illegal migration," said Grassley. He contended that the border security provisions in the bill don't amount to much because millions would get a provisional legal status once the Homeland Security Department has completed plans aimed at enhancing border security and fencing, even if the plans are flawed or inadequate.

"If enacted today, the bill would provide no pressure on this secretary or even any future secretary to secure the borders," Grassley contended.

Based on reporting by The Associated Press.

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