WASHINGTON (AP) — The Obama administration squared off with skeptical lawmakers Tuesday over efforts to terminate the government's authority to collect phone records of millions of Americans, a proposition that exposed sharp divisions among members of Congress.

With a vote nearing on amendments to a $598.3 million bill to fund the military, the White House raised the alarm over a move to end the National Security Agency's authority under the USA Patriot Act, preventing the secretive surveillance agency from collecting records unless an individual is under investigation.

And in an unusual, last-minute lobbying move, Gen. Keith Alexander, head of the NSA, traveled to Capitol Hill to urge lawmakers to oppose the amendment in separate, closed-door sessions with Republicans and Democrats.

"We oppose the current effort in the House to hastily dismantle one of our Intelligence Community's counterterrorism tools," White House press secretary Jay Carney said in a late-night statement. "This blunt approach is not the product of an informed, open or deliberative process."

Carney said President Barack Obama is still open to addressing privacy concerns in the wake of documents leaked last month by former NSA systems analyst Edward Snowden that revealed that the vast nature of the agency's phone and Internet surveillance. But he said Obama wants an approach that properly weighs what intelligence tools best keep America safe.

In another sign the White House was treating the measure with serious concern, its rebuke came directly from the press secretary, rather than the more routine notices from Obama's budget office the White House normally uses to weigh in on pending legislation.

The proposal offered by Rep. Justin Amash, R-Mich., dovetails with another amendment to the defense bill to cut off funds for the NSA. The House is likely to vote on the amendments Wednesday.

The fierce debate over privacy and national security has divided Congress, transcending the partisan lines that typically characterize legislative fights — especially in the House. Tea party conservatives and liberal Democrats have backed the amendments. But leaders from both parties have strongly defended the programs, including Senate Intelligence Committee Chairwoman Dianne Feinstein, D-Calif., and House Speaker John Boehner, R-Ohio

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At issue is where to draw the appropriate balance between national security in a post-9/11 America and the right to privacy that Americans expect to enjoy. National security hawks argue that the surveillance programs have helped disrupt numerous attempted terrorist attacks, and warn that future attacks will be harder to prevent if the programs are dismantled. But libertarians and others have contended that the programs constitute an overly broad intrusion into people's communications that, because they're kept secret, have little accountability.

The White House has tried to deflect criticism sparked by the Snowden revelations by arguing that it's taking steps to be as transparent as possible, including declassifying on Friday the fact that the secret court overseeing the programs had renewed an order authorizing part of the records collection. Obama has also discussed the programs with a federal privacy oversight panel.

Civil liberties advocates, however, have rejected those steps as too little, too late, pointing out that Americans would still be in the dark about the NSA's activities had they not been exposed by Snowden, whom the Justice Department is now pursuing on felony charges.

Alexander made the Tuesday trip to ask lawmakers to reject the amendments at the request of House Intelligence Committee Chairman Mike Rogers, R-Mich., and the committee's top Democrat, Rep. C.A. Dutch Ruppersberger of Maryland. The two also warned in a statement that ending the program's authority would put the nation at risk of another terrorist attack.

Separately, seven Republican committee chairmen sent a letter to colleagues calling on them to oppose the Amash amendment. Meanwhile, House Republican leaders struggled to limit amendments on the overall bill, concerned about hampering national security and anti-terrorism efforts.

The defense spending bill would provide the Pentagon with $512.5 billion for weapons, personnel, aircraft and ships plus $85.8 billion for the war in Afghanistan for the fiscal year beginning Oct. 1.

The bill is $5.1 billion below current spending and has drawn a veto threat from the White House, which argues that it would force the administration to cut education, health research and other domestic programs to boost spending for the Pentagon.

In a leap of faith, the bill assumes that Congress and the administration will resolve the automatic, across-the-board spending cuts that have forced the Pentagon to furlough workers and cut back on training. The bill projects spending in the next fiscal year at $28.1 billion above the so-called sequester level.

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Follow Donna Cassata at http://twitter.com/DonnaCassataAP and Josh Lederman at http://twitter.com/joshledermanAP