Wisconsin Rep. Paul Ryan, center, newly announced running mate of Republican presidential candidate, former Massachusetts Gov. Mitt Romney, greets the crowd while campaigning Saturday, Aug. 11, 2012 in Norfolk, Va. (AP Photo/Mary Altaffer)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (R) and U.S. Rep. Paul Ryan (R-WI) wave as Ryan is announced as his vice presidential running mate aboard the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

Republican presidential candidate, former Massachusetts Gov. Mitt Romney, right, and vice presidential candidate Wisconsin Rep. Paul Ryan, R-Wis., wave at the crowd during a campaign event, Saturday, Aug. 11, 2012 in Norfolk, Va. (AP Photo/Mary Altaffer)

Republican presidential candidate, former Massachusetts Gov. Mitt Romney, right, and vice presidential candidate Wisconsin Rep. Paul Ryan are joined by Ryan's daughter Liza as they wave to the crowd while campaigning Saturday, Aug. 11, 2012 in Norfolk, Va. (AP Photo/Mary Altaffer)

Republican presidential candidate, former Massachusetts Gov. Mitt Romney, right, and vice presidential candidate Wisconsin Rep. Paul Ryan, R-Wis., wave at the crowd during a campaign event, Saturday, Aug. 11, 2012 in Norfolk, Va. (AP Photo/Mary Altaffer)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (L) announces Rep. Paul Ryan (R-WI) (R) as his running mate in front of the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Win McNamee/Getty Images)

Mitt Romney and Rep. Paul Ryan together in Fitchburg, Wis., in March.

NORFOLK, VA - AUGUST 11: U.S. Rep. Paul Ryan (R-WI) speaks after being announced by Republican presidential candidate, former Massachusetts Gov. Mitt Romney as his running mate in front of the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Win McNamee/Getty Images)

NORFOLK, VA - AUGUST 11: U.S. Rep. Paul Ryan (R-WI) speaks after being announced by Republican presidential candidate, former Massachusetts Gov. Mitt Romney as his running mate in front of the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Win McNamee/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (R) and U.S. Rep. Paul Ryan (R-WI) wave as Ryan is announced as his vice presidential running mate aboard the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Win McNamee/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (R) and U.S. Rep. Paul Ryan (R-WI) wave as Ryan is announced as his vice presidential running mate aboard the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Win McNamee/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (C) arrives at the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Mitt Romney will announce Rep. Paul Ryan (R-WI), a seven term congressman, as his Vice President pick. Ryan is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (C) arrives at the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Mitt Romney will announce Rep. Paul Ryan (R-WI), a seven term congressman, as his Vice President pick. Ryan is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (L) jokes with Rep. Paul Ryan (R-WI) (R) after announcing him as the "next PRESIDENT of the United States" during an event announcing him as his running mate in front of the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Win McNamee/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (L) jokes with Rep. Paul Ryan (R-WI) (R) after announcing him as the "next PRESIDENT of the United States" during an event announcing him as his running mate in front of the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Win McNamee/Getty Images)

House Budget Committee Chairman Rep. Paul Ryan, R-Wis., listens to a question at the Heritage Foundation in Washington, Wednesday, Oct. 26, 2011. (AP Photo/Jacquelyn Martin)

Republican presidential candidate Mitt Romney in Des Moines, Iowa, Wednesday. File Photo. (AP Photo/Charles Dharapak)

FILE - House Budget Committee Chairman Rep. Paul Ryan, R-Wis. introduces Republican presidential candidate, former Massachusetts Gov. Mitt Romney before Romney spoke at the Grain Exchange in Milwaukee, in this April 3, 2012 file photo. Romney has picked Wisconsin congressman Paul Ryan to be his running mate, according to a Republican with knowledge of the development. They will appear together Saturday Aug. 11, 2012 in Norfolk, Va., at the start of a four-state bus tour to introduce the newly minted GOP ticket to the nation. (AP Photo/M. Spencer Green, File)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (R) waves to members of the media as he arrives at the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Mitt Romney will announce Rep. Paul Ryan (R-WI), a seven term congressman, as his Vice President pick. Ryan is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (R) and U.S. Rep. Paul Ryan (R-WI) wave as Ryan is announced as his vice presidential running mate aboard the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (R) and U.S. Rep. Paul Ryan (R-WI) wave as Ryan is announced as his vice presidential running mate aboard the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (L) and U.S. Rep. Paul Ryan (R-WI) (R) wave as Ryan is announced as his running mate aboard the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (R) greets Rep. Paul Ryan (R-WI) (L) after announcing him as his vice presidential running mate aboard the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

NORFOLK, VA - AUGUST 11: Republican presidential candidate, former Massachusetts Gov. Mitt Romney (R) and U.S. Rep. Paul Ryan (R-WI) wave as Ryan is announced as his vice presidential running mate aboard the USS Wisconsin August 11, 2012 in Norfolk, Virginia. Ryan, a seven term congressman, is Chairman of the House Budget Committee and provides a strong contrast to the Obama administration on fiscal policy. (Photo by Justin Sullivan/Getty Images)

US Republican presidential candidate and former Massachusetts Governor Mitt Romney announces Wisconsin Representative Paul Ryan(L) as his vice presidential running mate during a campaign rally at the Nauticus Museum after touring the USS Wisconsin in Norfolk, Virginia, August 11, 2012. Romney and his new running mate embark on the first day of a 4-day bus trip that will take the White House hopefuls to 4 key swing states, Virginia, North Carolina, Florida and Ohio. AFP PHOTO / Saul LOEBSAUL LOEB/AFP/GettyImages

US Republican presidential candidate and former Massachusetts Governor Mitt Romney announces Wisconsin Representative Paul Ryan(L) as his vice presidential running mate during a campaign rally at the Nauticus Museum after touring the USS Wisconsin in Norfolk, Virginia, August 11, 2012. Romney and his new running mate embark on the first day of a 4-day bus trip that will take the White House hopefuls to 4 key swing states, Virginia, North Carolina, Florida and Ohio. AFP PHOTO / Saul LOEBSAUL LOEB/AFP/GettyImages

US Republican presidential candidate and former Massachusetts Governor Mitt Romney announces Wisconsin Representative Paul Ryan(L) as his vice presidential running mate during a campaign rally at the Nauticus Museum after touring the USS Wisconsin in Norfolk, Virginia, August 11, 2012. Romney and his new running mate embark on the first day of a 4-day bus trip that will take the White House hopefuls to 4 key swing states, Virginia, North Carolina, Florida and Ohio. AFP PHOTO / Saul LOEBSAUL LOEB/AFP/GettyImages

US Republican presidential candidate and former Massachusetts Governor Mitt Romney announces Wisconsin Representative Paul Ryan(R) as his vice presidential running mate during a campaign rally at the Nauticus Museum after touring the USS Wisconsin in Norfolk, Virginia, August 11, 2012. Romney and his new running mate embark on the first day of a 4-day bus trip that will take the White House hopefuls to 4 key swing states, Virginia, North Carolina, Florida and Ohio. AFP PHOTO / Saul LOEBSAUL LOEB/AFP/GettyImages

US Republican presidential candidate and former Massachusetts Governor Mitt Romney(R) announces Wisconsin Representative Paul Ryan as his vice presidential running mate during a campaign rally at the Nauticus Museum after touring the USS Wisconsin in Norfolk, Virginia, August 11, 2012. Romney and his new running mate embark on the first day of a 4-day bus trip that will take the White House hopefuls to 4 key swing states, Virginia, North Carolina, Florida and Ohio. AFP PHOTO / Saul LOEBSAUL LOEB/AFP/GettyImages

US Republican presidential candidate and former Massachusetts Governor Mitt Romney and Wisconsin Representative Paul Ryan(C), along with his daughter Liza, prepare to board the campaign bus after announcing Ryan as his vice presidential running mate during a campaign rally at the Nauticus Museum after touring the USS Wisconsin in Norfolk, Virginia, August 11, 2012. Romney and his new running mate embark on the first day of a 4-day bus trip that will take the White House hopefuls to 4 key swing states, Virginia, North Carolina, Florida and Ohio. AFP PHOTO / Saul LOEBSAUL LOEB/AFP/GettyImages