Lawmakers are pledging to investigate the National Security Administration's practice of collecting the phone and Internet records of millions of Americans.

Aides to House leaders told The Washington Examiner that members of Congress will receive a classified briefing on the matter Tuesday from the NSA, the FBI, the Justice Department and the office of the director of national intelligence.

House Majority Leader Eric Cantor, R-Va., promised a "very serious" congressional investigation into the NSA activities, including how a government contractor was allowed access to classified information he then leaked to two newspapers.

Edward Snowden, 29, a recent hire at government contractor Booz Allen Hamilton, stepped forward Sunday as the man who went public with information about the classified surveillance program, which he said would have allowed him to tap into virtually anyone's call or email, whether in the private sector or U.S. government.

Snowden fled to Hong Kong, though it's not clear whether that's his final destination.

"We don't know the answers, and that's why I think this week on Capitol Hill is going to be very, very important," Cantor told CBS news. "The administration is responsible for implementing this program. The Congress is responsible for the oversight of this program. The investigations will be very serious, obviously. We'll be dealing with the balance between national security and safeguarding our civil liberties."

White House press secretary Jay Carney on Monday defended Obama against accusations that he allowed a secret, massive invasion of Americans' privacy.

"I think that the president's record on transparency is broad and significant," Carney said, adding that there is a "balance necessary" to protect the nation from terrorism.

Carney reiterated Obama's claim that some congressional lawmakers had been briefed on the NSA surveillance, including Senate Intelligence Committee Chairwoman Dianne Feinstein, D-Calif., who is now publicly defending the surveillance program.

The new disclosure of the surveillance program has renewed the debate over the Patriot Act, a sweeping anti-terrorism law passed shortly after the Sept. 11, 2001, terrorist attack that gave the NSA the authority to conduct domestic surveillance. Some lawmakers say the Patriot Act should be reconsidered. It was last renewed in May 2011 and the extension included a provision allowing for roving wiretaps

A Pew Research poll released on Monday found that 56 percent of Americans believed the NSA surveillance program "is an acceptable way for the government to investigate terrorism," while 41 percent call it unacceptable.

Snowden said that after growing disillusioned with Obama, he became a fan of libertarian Ron Paul's presidential campaign in 2012.

Paul put out a statement saying "we should be thankful" for Snowden and Guardian reporter Glenn Greenwald, who broke the story.

"They have done a great service to the American people by exposing the truth about what our government is doing in secret," said Paul.

But many lawmakers, including Feinstein, say Snowden committed an act of treason and should be prosecuted for leaking classified information.