With her elegant outfits and perfectly coiffed blonde hair, Cindy McCain looks the part of a US First Lady.

She is also well prepared for the role.

Heiress to a fortune estimated at more than $100 million and chairman of one of the largest privately held companies in Arizona, McCain has travelled overseas extensively with different philanthropic organisations, visiting Cambodia, Sri Lanka, Angola, India, Vietnam and other countries.

She has dealt with US government agencies, championed relief work through her charities and overseen the family business, gaining valuable experience that would serve her well as First Lady if her husband, Republican John McCain, wins the presidential election on Tuesday.

"Despite the fact that she hasn't been in Washington, DC, all that much, her actual experience in foreign countries would be the greatest attribute to serve her well," said Carl Sferrazza Anthony, author and historian for the National First Ladies Library. Anthony said McCain's international experience as the medical charity's founder and board member for a non-profit landmine removal group, will give her a boost at the White House.

"She's had to deal with government agencies... and I think in the process she has developed a certain level of diplomacy that I think is along the lines of what might be asked of her were she to be First Lady," Anthony said.

McCain, 54, has indicated she would continue her philanthropic work if her husband wins, although it is unclear what she would do with her role in the family business, Hensley and Co., one of the largest US beer distributors.

McCain is a former rodeo queen and cheerleader who holds a master's degree in special education from the University of Southern California.

Eighteen years younger than her husband, McCain has an independent streak.

She never moved to Washington although her husband has been in Congress for most of their married life.

She likes to tell a story of how she came home from a trip to Bangladesh with a baby she planned to adopt.

She only told her husband when she landed in the United States.

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