President Barack Obama is briefed on the situation in Libya by John Brennan, Assistant to the President for Homeland Security and Counterterrorism, in Chilmark, Mass., Aug. 26, 2011.

President Barack Obama is briefed on the situation in Libya by John Brennan, Assistant to the President for Homeland Security and Counterterrorism, in Chilmark, Mass., Aug. 26, 2011.

President Barack Obama holds conference call on Hurricane Irene with FEMA Administrator Craig Fugate, Homeland Security Secretary Janet Napolitano, Chief of Staff Bill Daley, and John Brennan, Assistant to the President for Homeland Security, in Chilmark, Mass., Aug. 26, 2011. (Official White House Photo by Pete Souza) This official White House photograph is being made available only for publication by news organizations and/or for personal use printing by the subject(s) of the photograph. The photograph may not be manipulated in any way and may not be used in commercial or political materials, advertisements, emails, products, promotions that in any way suggests approval or endorsement of the President, the First Family, or the White House.

President Barack Obama holds conference call on Hurricane Irene with FEMA Administrator Craig Fugate, Homeland Security Secretary Janet Napolitano, Chief of Staff Bill Daley, and John Brennan, Assistant to the President for Homeland Security, in Chilmark, Mass., Aug. 26, 2011.
(Official White House Photo by Pete Souza)

This official White House photograph is being made available only for publication by news organizations and/or for personal use printing by the subject(s) of the photograph. The photograph may not be manipulated in any way and may not be used in commercial or political materials, advertisements, emails, products, promotions that in any way suggests approval or endorsement of the President, the First Family, or the White House.

President Barack Obama receives an economic briefing from Brian Deese, Deputy Director of the National Economic Council, in Chilmark, Mass., August 24, 2011. This official White House photograph is being made available only for publication by news organizations and/or for personal use printing by the subject(s) of the photograph. The photograph may not be manipulated in any way and may not be used in commercial or political materials, advertisements, emails, products, promotions that in any way suggests approval or endorsement of the President, the First Family, or the White House. (Official White House Photo by Pete Souza)

President Barack Obama receives an economic briefing from Brian Deese, Deputy Director of the National Economic Council, in Chilmark, Mass., August 24, 2011.

This official White House photograph is being made available only for publication by news organizations and/or for personal use printing by the subject(s) of the photograph. The photograph may not be manipulated in any way and may not be used in commercial or political materials, advertisements, emails, products, promotions that in any way suggests approval or endorsement of the President, the First Family, or the White House.
(Official White House Photo by Pete Souza)

President Barack Obama receives a national security briefing from John Brennan, Assistant to the President for Homeland Security, in Chilmark, Mass., Aug. 19, 2011.

President Barack Obama receives a national security briefing from John Brennan, Assistant to the President for Homeland Security, in Chilmark, Mass., Aug. 19, 2011.

President Barack Obama kayaks while spending time with friends at a beach in Edgartown, Mass., Aug. 28, 2010.

President Barack Obama kayaks while spending time with friends at a beach in Edgartown, Mass., Aug. 28, 2010.

The white draped casket of Senator Edward Kennedy sits before (from left) the Senator’s son Edward Kennedy Jr., his widow Vicki Kennedy, former President Bill Clinton, Secretary of State Hillary Clinton, former president George W. Bush, President Barack Obama and First Lady Michelle Obama, Vice President Joseph Biden and his wife Jill Biden, and former First Lady Rosalynn Carter and former President Jimmy Carter during funeral services at the Basilica of Our Lady of Perpetual Help in Boston, Mass. on Aug. 29, 2009.

The white draped casket of Senator Edward Kennedy sits before (from left) the Senator's son Edward Kennedy Jr., his widow Vicki Kennedy, former President Bill Clinton, Secretary of State Hillary Clinton, former president George W. Bush, President Barack Obama and First Lady Michelle Obama, Vice President Joseph Biden and his wife Jill Biden, and former First Lady Rosalynn Carter and former President Jimmy Carter during funeral services at the Basilica of Our Lady of Perpetual Help in Boston, Mass. on Aug. 29, 2009.

President Barack Obama looks down the fairway while golfing at Vineyard Golf Club near Lobsterville Beach during his vacation on Martha’s Vineyard, Aug. 27, 2009.

President Barack Obama looks down the fairway while golfing at Vineyard Golf Club near Lobsterville Beach during his vacation on Martha's Vineyard, Aug. 27, 2009.

President Barack Obama and family tour the Gay Head lighthouse in Aquinnah, Mass., while on vacation on Martha’s Vineyard, Aug. 27, 2009.

President Barack Obama and family tour the Gay Head lighthouse in Aquinnah, Mass., while on vacation on Martha's Vineyard, Aug. 27, 2009.

President Barack Obama plays basketball with White House staffers while on vacation on Martha’s Vineyard, Aug. 26, 2009.

President Barack Obama plays basketball with White House staffers while on vacation on Martha's Vineyard, Aug. 26, 2009.

People wave at President Barack Obama during the family’s vacation on Martha’s Vineyard, Aug. 25 2009.

People wave at President Barack Obama during the family's vacation on Martha's Vineyard, Aug. 25 2009.