David Axelrod, a top adviser to President Obama, hit back forcefully at allegations that the White House deliberately leaked sensitive national security information.

Attorney General Eric Holder has appointed two prosecutors to investigate the sources behind a pair of front page New York Times articles which quoted dozens of current and former Obama administration officials and revealed intricate details about the White House's "kill list" and its cyberattacks on Iran.

Congressional Republicans have accused the White House of leaking the information to bolster Obama's political standing on national security issues.

On Friday, Obama said that such an idea was "offensive" to him, and pledged that the source of the leaks would be rooted out.

On Sunday, George Stephanopoulos pointed out to Axelrod that both Times stories are sourced at an apparently high level within the administration.

"In both cases, they quote members of the president's national security team who were in the room," Stephanopoulos said. "So somebody who was in the room with the president was giving out some of this information or at least discussing classified information."

"I think the authors of all of this work have said that the White House was not the source of this information," Axelrod replied. "I can't say that there weren't leaks. There were obvious leaks, but they weren't from the White House."

He said that "life or death decisions" weigh "heavily" on Obama.

"The last thing that he would countenance or anybody around him would countenance are leaks that would jeopardize the security of Americans on these secret missions, and the success of those missions."

"So you're confident this investigation's not going to show White House involvement?" Stephanopoulos said.

"Yes," Axelrod said. He touted the Obama administration's unprecedented crackdown on whistleblowers and reporters over leaks as proof that the White House meant business.

"We have come under attack because we have been tougher on leaks than any administration in recent history, and we have been criticized for that," Axelrod said.

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  • Dianne Feinstein, Saxby Chambliss, Mike Rogers, C.A. "Dutch" Ruppersberger

    After a closed-door meeting with National Intelligence Director James Clapper, the four leaders of the House and Senate Intelligence Committees hold a news conference, on Capitol Hill in Washington, Thursday, June 7, 2012, to discuss the recent spate of classified national security information leaks. From left are Rep. C.A. "Dutch" Ruppersberger, D-Md., the ranking Democrat on the House Intelligence Committee; House Intelligence Committee Chairman Mike Rogers, R-Mich., Sen. Saxby Chambliss, R-Ga., vice-chair of the Senate Intelligence Committee, and Senate Intelligence Committee Chair Sen. Dianne Feinstein, D-Calif. (AP Photo/J. Scott Applewhite)

  • Dianne Feinstein, Saxby Chambliss, Mike Rogers, C.A. "Dutch" Ruppersberger

    After a closed-door meeting with National Intelligence Director James Clapper, the four leaders of the House and Senate Intelligence Committees hold a news conference, on Capitol Hill in Washington, Thursday, June 7, 2012, to discuss the recent spate of classified national security information leaks. From left Rep. C.A. "Dutch" Ruppersberger, D-Md., the ranking Democrat on the House Intelligence Committee; House Intelligence Committee Chairman Rep. Mike Rogers, R-Mich., Senate Intelligence Committee Chair Sen. Dianne Feinstein, D-Calif.; and Sen. Saxby Chambliss, R-Ga., vice-chair of the Senate Intelligence Committee. (AP Photo/J. Scott Applewhite)

  • Dianne Feinstein, Saxby Chambliss, Mike Rogers, C.A. "Dutch" Ruppersberger

    After a closed-door meeting with National Intelligence Director James Clapper, the four leaders of the House and Senate Intelligence Committees hold a news conference, on Capitol Hill in Washington, Thursday, June 7, 2012, to discuss the recent spate of classified national security information leaks. From left are, Rep. C.A. "Dutch" Ruppersberger, D-Md., the ranking Democrat on the House Intelligence Committee; House Intelligence Committee Chairman Rep. Mike Rogers, R-Mich., Senate Intelligence Committee Chair Sen. Dianne Feinstein, D-Calif.; and Sen. Saxby Chambliss, R-Ga., vice-chair of the Senate Intelligence Committee. (AP Photo/J. Scott Applewhite)

  • James Clapper

    Director of National Intelligence James Clapper, center, emerges from a closed-door meeting with the House and Senate Intelligence Committees aimed at stopping security leaks, Thursday, June 7, 2012, on Capitol Hill in Washington. (AP Photo/J. Scott Applewhite)

  • James Clapper

    Director of National Intelligence James Clapper, center, emerges from a closed-door meeting with the House and Senate Intelligence Committees aimed at stopping security leaks, Thursday, June 7, 2012, on Capitol Hill in Washington. (AP Photo/J. Scott Applewhite)

  • Jay Carney

    Press Secretary Jay Carney briefs reporters at the White House in Washington, Monday, June 4, 2012. (AP Photo/Charles Dharapak)

  • House Leader Boehner And Cantor Respond To Obama's Economic News Conference

    WASHINGTON, DC - JUNE 08: House Majority Leader Eric Cantor (R-VA) (L) and U.S. Speaker of the House John Boehner (R-OH) (R) respond to U.S. President Barack Obama's remarks on the U.S. economy June 8, 2012 in Washington, DC. During their remarks, Cantor said, 'Did he see the job numbers that came out last week? The private sector is not doing fine. And, frankly, I'd ask the president to stop engaging in the blame game.' (Photo by Win McNamee/Getty Images)

  • House Leader Boehner And Cantor Respond To Obama's Economic News Conference

    WASHINGTON, DC - JUNE 08: House Majority Leader Eric Cantor (R-VA) (L) and U.S. Speaker of the House John Boehner (R-OH) (R) respond to U.S. President Barack Obama's remarks on the U.S. economy June 8, 2012 in Washington, DC. During their remarks, Cantor said, 'Did he see the job numbers that came out last week? The private sector is not doing fine. And, frankly, I'd ask the president to stop engaging in the blame game.' (Photo by Win McNamee/Getty Images)

  • House Leader Boehner And Cantor Respond To Obama's Economic News Conference

    WASHINGTON, DC - JUNE 08: U.S. Speaker of the House John Boehner (R-OH) arrives to respond to U.S. President Barack Obama's remarks on the U.S. economy June 8, 2012 in Washington, DC. During remarks with House Majority Leader Eric Cantor, Cantor said, 'Did he see the job numbers that came out last week? The private sector is not doing fine. And, frankly, I'd ask the president to stop engaging in the blame game.' (Photo by Win McNamee/Getty Images)

  • House Leader Boehner And Cantor Respond To Obama's Economic News Conference

    WASHINGTON, DC - JUNE 08: House Majority Leader Eric Cantor (R-VA) (L) and U.S. Speaker of the House John Boehner (R-OH) (R) respond to U.S. President Barack Obama's remarks on the U.S. economy June 8, 2012 in Washington, DC. During their remarks, Cantor said, 'Did he see the job numbers that came out last week? The private sector is not doing fine. And, frankly, I'd ask the president to stop engaging in the blame game.' (Photo by Win McNamee/Getty Images)

  • House Leader Boehner And Cantor Respond To Obama's Economic News Conference

    WASHINGTON, DC - JUNE 08: U.S. Speaker of the House John Boehner (R-OH) (R) and House Majoirty Leader Eric Cantor (R-VA) (L) respond to U.S. President Barack Obama's remarks on the U.S. economy June 8, 2012 in Washington, DC. During Cantor's remarks, Cantor said, 'Did he see the job numbers that came out last week? The private sector is not doing fine. And, frankly, I'd ask the president to stop engaging in the blame game.' (Photo by Win McNamee/Getty Images)