Republican presidential candidate Sen. John McCain, accompanied by his wife Cindy, right, greets the crowd at Wings over Meridian Air Show in Mississippi. (Mary Altaffer / Associated Press)
Republican presidential candidate, Sen. John McCain, followed by his daughter Meghan, exits his airplane in Las Vegas. (Mary Altaffer / Associated Press)
Republican presidential candidate Sen. John McCain speaks to reporters during a news conference in Las Vegas. (Mary Altaffer / Associated Press)
Sen. Barack Obama is on a six-day “Road to Change” bus tour through Pennsylvania to campaign for the upcoming state’s primary. (Alex Wong / Getty Images)
Supporters of Democratic presidential hopeful Sen. Barack Obama listen as he speaks during a town hall meeting at the Pennsylvania State Capitol Complex in Harrisburg. (Alex Wong / Getty Images)
Democratic Presidential hopeful Sen. Barack Obama greets supporters after a town hall meeting in Harrisburg, a stop on his six-day bus tour of Pennsylvania. (Stan Honda / AFP/Getty Images)
Democratic presidential hopeful Sen. Hillary Rodham Clinton campaigns at DuPont Manual High School in Louisville, Ky. (Charles Dharapak / Associated Press)
Democratic presidential hopeful Sen. Hillary Rodham Clinton campaigns at Sara’s Diner in Fort Wayne, Ind. (Charles Dharapak / Associated Press)
