In an effort to connect with struggling families and combat attempts by his opponents to paint him as elite, Obama has sought to remind voters on the campaign trail that he grew up with economic uncertainty.
"Our parents weren't wealthy by any means," Obama told voters at a campaign stop in Denver last May. "My mother raised my sister and me on her own, and she even had to use food stamps at one point."
"I don't come from money, I don't come from a lot of privilege. When I see a single mom somewhere trying to raise their children, I know what that's like. When a family can't afford college, I know what that's like," Obama told a crowd in Las Vegas during the Democratic primaries.
In Obama's first memoir, "Dreams From My Father," he wrote that his private school classmates sometimes commented on the lack of food in the family refrigerator.
The presumptive Democratic nominee was born in Hawaii to Barack Obama Sr., a black foreign student from Kenya and Ann Dunham, a white woman from Kansas. The father left the family when his son was 2 years old, and Obama was raised by his mother until she remarried and moved the family to her new husband's home country of Indonesia, when Obama was 6.
He began living with his mother's parents when he was 10, and they helped to send him to a prestigious private school. After a stint at Occidental College, where Obama dabbled in drugs and alcohol, he graduated from Columbia University and Harvard Law School. Obama said he paid for his higher education by taking out student loans that he has said he carried into adulthood.
Obama was a community organizer in Chicago, a civil rights litigator and a constitutional law professor before he won a seat in the Illinois State Senate and later, a seat in the U.S. Senate in 2004.
McCain's campaign has also tried to refocus on economic issues in recent days, advocating off-shore oil drilling and mocking Obama's suggestion that drivers inflate their tires properly to conserve gas.
The presumptive Republican nominee, whose economic agenda has focused on weaning the nation off foreign oil, toured a nuclear power plant in Michigan Tuesday to highlight his support for the construction of 45 new nuclear power generators by 2030.
He has also proposed giving $300 million to a company that develops an effective hybrid car battery.
Obama has blasted McCain for quipping during the primaries that the economy is not his strong suit -- something advisers characterize as an example of McCain's self-depreciatory style.
McCain's campaign also struggled with message control last month when former Sen. Phil Gramm, R- Texas, speaking as a senior economic adviser for McCain, said in an interview that the nation was suffering from only a "mental recession" and not an actual one. McCain quickly distanced himself from Gramm, who has since stepped down from his advisory role in McCain's campaign.
Growing up, McCain's family lived a military lifestyle, and moved often across the United States and the Pacific.
In McCain's family memoir, "Faith of My Fathers," written with McCain's longtime aide Mark Salter, the Arizona senator describes his childhood, shuttling from Navy base to Navy base under the shadows of his father, a decorated submarine commander, and his grandfather, also a well-respected top Navy official.