Rudolph Giuliani, 62, served two terms as mayor of New York City, during which time he earned the nickname 'America's Mayor' for his leadership after the September 11, 2001 terrorist attacks. Giuliani served as a federal prosecutor before becoming mayor and he currently heads his own consulting firm for emergency preparedness, public safety, and crisis management.

Michael Huckabee, 51, served as governor of Arkansas from 1996 to 2007. He also served as Lieutenant Governor and chairman of the National Governors' Association. A significant part of his adult life was spent as a pastor of several Southern Baptist churches and he is the youngest person ever to serve as president of the Arkansas Baptist State Convention.

Senator John McCain, 70, was first elected to the U.S. Senate in 1987 after serving four years in the U.S. House. McCain is a Vietnam War veteran and a former POW who spent more than five years in the brutal and infamous 'Hanoi Hilton.' Senator McCain also ran for president in 2000 but lost to then-Governor George W. Bush for the Republican nomination.

Representative Ron Paul, 71, is a 10 term Congressman representing the 14th Congressional District in Texas, covering an area southwest of Houston, including Galveston. Representative Paul ran as the Libertarian Party nominee for President in 1988.

Mitt Romney, 60, served one term as the Governor of Massachuseetts from 2003 to 2007. Before his political career, Governor Romney gained national attention for his role in turning around the 2002 Winter Olympics in Salt Lake City which was mired in controversy and facing financial crisis. He is also a former CEO of the management and consulting firm Bain & Company.