Background: Born Laura Welch in Midland, Texas. An only child, trained as a teacher and taught in public schools in Texas before taking librarianship master's degree and becoming school librarian.
Family: Met and married George W Bush in 1977. The couple have twin daughters, Barbara and Jenna, named for their grandmothers.
Political experience: Has used position as first lady of Texas, then of the US, to encourage education initiatives, particularly reading. Despite winning promise she would never have to make a speech for her husband, has become a regular on the campaign trail.
Influence on husband: Forbes Magazine named Mrs Bush the world's fourth most powerful woman in August 2004 because of her closeness to her husband. While never challenging him in public, she is believed to let him know when she thinks he is off the mark.
Pros: Seen as above the political fray, far more of a traditional First Lady than either her predecessor, Hillary Rodham Clinton, or her would-be replacement. Her approval ratings remain high as she moves away from favourite education issues to promote her husband's policies on the economy and law reform.
Cons: Not a polished or keen campaigner, but has used that to her advantage.
A memorable quote:
"It's me or the bottle." Ultimatum allegedly given to her husband on his 40th birthday.
Teresa Heinz Kerry
Background: Born in Mozambique, studied in South Africa and Switzerland. Moved to the US and got a job at the United Nations. Fluent in several languages.
Family: Married Senator John Heinz in 1966 and had three sons with him. Widowed in 1991 when Heinz was killed in a plane crash. His estate - he was heir to the Heinz ketchup fortune - left her very wealthy. Married John Kerry in 1995.
Political experience: Rejected calls to stand for Heinz's Senate seat after his death. Became involved in non-governmental organisations under Heinz Family Philanthropies. Appointed by President George Bush Snr to represent US NGOs at the Rio Earth Summit. Presented with Albert Schweitzer Gold Medal.
Influence on husband: Mutual interest in the environment brought them together and she is a strong supporter of his policies. But while he is certain to know her views, the extent to which she modifies them is not known.
Pros: One of the best promoters of her husband. Experienced in campaigning for the environment, health care, women's rights and the arts.
Cons: Unconventional and may cause unease. Many know her only as the caricature - a forthright, outspoken woman who told a reporter she believed hostile to "shove it".
A memorable quote:
"I hope it will come as no surprise to anyone that I have something to say." Starting her speech at the Democrats' convention.