Hillary Diane Rodham was born in Chicago, Oct. 26, 1947, the daughter of Hugh and Dorothy Howell Rodham. She is a graduate of Wellesley College and Yale Law School.
After graduation, Hillary Rodham moved to Arkansas and married Bill Clinton, a Yale classmate who would later become governor of Arkansas and the 42nd president of the United States. They have one daughter, Chelsea.
In Arkansas, Hillary Clinton ran a legal aid clinic for the poor, became a partner with the Rose Law Firm in Little Rock and led a task force to improve the public schools.
As first lady from 1993 to 2001, she led a task force on health care reform and wrote three books, It Takes a Village and Dear Socks, Dear Buddy: Kids' Letters to the First Pets and An Invitation to the White House. She would later write a memoir, Living History. Both she and Barack Obama have won Grammy Awards for spoken-word recordings of their books.
In her final months in the White House, Hillary Clinton was elected to the U.S. Senate from New York. She was re-elected in 2006. She is a Methodist.
Barack Hussein Obama was born Aug. 4, 1961, in Honolulu, the son of Barack Obama Sr., a native of Kenya, and Ann Dunham Obama, a native of Kansas.
Obama attended Occidental College in Los Angeles, then graduated from Columbia University in 1983. He worked as a community organizer with a church-based group in Chicago, then attended Harvard Law School, where he was the first black president of the Harvard Law Review.
After graduation, he returned to Chicago to practice as a civil rights lawyer and teach constitutional law at the University of Chicago.
He was elected to the Illinois State Senate in 1996 and served for eight years. In 2004, he was the keynote speaker at the Democratic National Convention in Boston and won a race for the U.S. Senate, only the third African-American elected since Reconstruction. He is the author of two best-selling books, Dreams From My Father and The Audacity of Hope.
He and his wife, Michelle, have two daughters, Malia and Sasha. They are members of Trinity United Church of Christ.
Michael Dale Huckabee was born in Hope, Ark., Aug. 24, 1955, the son of Dorsey W. and Mae Elder Huckabee. He is a graduate of Ouachita Baptist University in Arkadelphia, Ark., and did postgraduate work at Southwestern Baptist Theological Seminary in Fort Worth, Texas.
Ordained three decades ago, Huckabee has been the pastor of three Southern Baptist churches in Arkadelphia, Pine Bluff and Texarkana, Ark.
He won a special election in 1993 to become Arkansas' lieutenant governor and moved up to governor in July 1996 with the resignation of Democrat Jim Guy Tucker. He was elected to four-year terms in 1998 and 2002.
He and his wife of 33 years, Janet McCain Huckabee, have three children: John Mark, David and Sarah.
Before running for the White House, Huckabee was perhaps best known for the 110 pounds he lost after being diagnosed with Type 2 Diabetes. He has run in marathons since then. He also plays bass guitar in a rock 'n' roll band, Capitol Offense.
John Sidney McCain III was born in the Panama Canal Zone, Aug. 29, 1936, the son of John S. McCain Jr. and Roberta Wright McCain.
McCain, whose father and grandfather were prominent admirals, is a 1958 graduate of the U.S. Naval Academy in Annapolis. He became a decorated Navy pilot and served in Vietnam. During his 23rd bombing mission on Oct. 26, 1967, his plane was hit by a missile, and he was forced to eject. He spent 5 1/2 years as a prisoner of the North Vietnamese.
After his return to the United States, McCain became the naval liaison to the U.S. Senate. He retired from the Navy in 1981 and was elected to Congress from Arizona the next year. He was elected to the Senate in 1986 and is serving his fourth term.
McCain and his second wife, Cindy Hensley McCain, have four children: Megan, Jack, James and Bridget. McCain has three children from his first marriage - Doug, Andy and Sydney - and four grandchildren. He is an Episcopalian.
Ronald Ernest Paul was born Aug. 20, 1935, in Pittsburgh, the son of Howard Casper Paul and Margaret Dumont Paul. He graduated from Gettysburg College and Duke University School of Medicine, then served as a flight surgeon in the Air Force during the 1960s.
After leaving the military, Paul moved to Texas and established a medical practice. An obstetrician-gynecologist, he has delivered more than 4,000 babies.
Paul won a special election for the U.S. House of Representatives in 1976 but lost the general election. He was elected in 1978, 1980 and 1982, then lost a race for the Senate in 1984. He was the Libertarian nominee for president in 1988. Re-elected to the House in 1996, he is serving his sixth consecutive term.
He and his wife of 51 years, Carol Wells Paul, have five children: Ronald Jr., Lori Paul Pyeatt, Randall, Robert and Joy Paul-Le Blanc; 18 grandchildren; and one great-grandchild. Paul is a Protestant.