Kerry spent much of his childhood abroad, attending boarding school in Switzerland and New Hampshire before entering Yale University.

At Yale, Kerry was a top debater, president of the political union, and, like both President Bushes, a member of the Skull & Bones secret society. In 1965 Kerry committed to join the Navy after graduating from college, essentially volunteering for service in Vietnam. At the end of his senior year in 1966, he was selected to give the class oration. Kerry delivered what political reporter Joe Klein called "a broad, passionate criticism of American foreign policy, including the war he would soon be fighting."

In Vietnam Kerry served as a "swift boat" captain, and was in charge of ferrying soldiers and supplies up the Mekong River. The small boats were easy targets for ambush from enemy soldiers on the banks of the river, and often took fire as they sped through hostile territory.

Tiring of the attacks, Kerry proposed to his men that they launch a counterattack against ambushers by quickly turning the boats directly toward the point of gunfire and rushing the enemy position. On Feb. 28, 1969, Kerry and his crew successfully executed his counterattack plan, capturing and killing enemy soldiers. Kerry himself chased down and killed a soldier carrying a rocket launcher.

"When the firing began I gave the order to turn and -- phoom! -- we just went in and beached and took them by complete surprise, and we routed them and we didn't take a wound," Kerry said in a 2002 New Yorker profile by Klein.

For his service in Vietnam, Kerry would be awarded a Silver Star, a Bronze Star with Combat V (for valor), and three Purple Hearts for being wounded in battle three times.

After his tour of duty, Kerry again spoke out against the U.S. involvement in the war and became a leading activist. The senator's official Web site says, "he felt compelled to question decisions he believed were being made to protect those in positions of authority in Washington at the expense of the soldiers carrying on the fighting in Vietnam."

Kerry helped found Vietnam Veterans of America and served as the spokesperson for Vietnam Veterans Against the War.

"How do you ask a man to be the last man to die in Vietnam? How do you ask a man to be the last man to die for a mistake?" he once famously asked the Senate Foreign Relations Committee.

During a 1971 antiwar protest, Kerry threw some of his military decorations onto the steps of the U.S. Capitol.

Kerry's involvement in the antiwar movement marked the opening steps in his political career. Some analysts and writers thought him precociously ambitious. In a 60 Minutes television interview during this period, Morley Safer asked Kerry point blank, "Do you want to be president?" Kerry replied with a "no" and a laugh.

In 1972, after what political analyst Michael Barone called "some widely observed district shopping," Kerry ran for a Massachusetts congressional seat and lost. After the campaign he entered law school at Boston College, and after graduating in 1976 went to work as an assistant district attorney for Middlesex County, Massachusetts.

Kerry first won statewide political office in 1982, when he ran for lieutenant governor on the same ticket as Michael Dukakis. In 1984 Kerry won his current U.S. Senate seat, defeating Republican Raymond Shamie 55 to 45 percent. Kerry was reelected in 1990, defeating GOP challenger Jim Rappaport 57 percent to 43 percent.

In the Senate, Kerry has built a reputation as a left-of-center legislator. Klein reported that Kerry votes with senior Massachusetts Sen. Ted Kennedy, a well-known liberal, "about 96 percent of the time."

"But it's important to look at the other 4 percent," David McKean, Kerry's chief of staff told Klein.

Barone writes that there are differences of "nuance and interest" between Kennedy and Kerry, citing the junior senator's support for free trade and his inclination to support "an expansive U.S. foreign and military policy."

Kerry has also been critical of the bureaucracy of public education and teacher tenure in opposition to teacher's unions, which traditionally support Democratic candidates.

In the Senate, Kerry has also become an influential member of a bipartisan fraternity -- Vietnam veterans. Republican Sen. John McCain of Arizona is one of his closest friends in the body. Kerry led a Senate committee that concluded no U.S. soldiers were still being held as prisoners in Vietnam, and Kerry and McCain worked with the Clinton administration to normalize relations with Vietnam in 1995.

In 1996 popular Massachusetts GOP Gov. William Weld challenged Kerry for his Senate seat. The campaign "was the rarest of events in latter-day American politics: a civil, closely contested, intelligent and wildly entertaining brawl," wrote Klein. Kerry narrowly defeated Weld 52 percent to 45 percent.

In 2002 Kerry cruised to reelection, defeating Libertarian candidate Michael Cloud 80 percent to 18 percent.

Kerry has been a critic of President Bush's domestic and foreign policy. Kerry voted against the tax cuts the administration advocated, against the proposal to drill for oil in Alaska's Arctic National Wildlife Refuge coastal area, and against approving the nomination of Attorney General John Ashcroft.

Kerry has staked his claim to the presidency, however, on criticism of the administration's foreign policy, especially its handling of the Iraq war. He has argued that Democrats must take the foreign policy debate back from their GOP rivals.

Fellow candidate and former Vermont Gov. Howard Dean has criticized Kerry for voting to give the president broad authority to wage war in Iraq and later criticizing the administration's policies there. Kerry voted against the $87 billion aid package President Bush requested for Iraq in October.

Kerry's response is that the president has misused the trust that Congress placed in him.

"The president made promises to us -- that he would build a coalition, that he would respect the U.N. and go through the international inspection process, and that he would only go to war as a last resort," Kerry has said, according to The New York Times.

Kerry has stood by his early vote on authorization while continually criticizing the president's handling of foreign policy.

"Overseas, George Bush has led and misled us on a course at odds with 200 years of our history," Kerry said on Sept. 2, the day he officially launched his campaign in Mt. Pleasant, S.C. "He has squandered the goodwill of the world after Sept. 11 and he has lost the respect and influence needed to make our country safe."

In 1995 Kerry, who was divorced at the time, married the widow of former fellow senator John Heinz of Pennsylvania. Teresa Heinz, a former Republican, is heir to the Heinz fortune.

Kerry has said in the past that if other candidates launch media attacks against him during the campaign, he might use some of his wife's money to respond, but it is unclear how much would be available. Teresa Heinz controls a reported $550 million to $600 million, but much of that may not be available for Kerry's political use.

"A big chunk of Mrs. Kerry's fortune could be off-limits," Business Week reported in the summer of 2003. "Campaign finance analysts say candidates are allowed to use unlimited amounts of their own cash, but they cannot spend assets that belong to a family member."

In February 2003 Kerry left the campaign trail to undergo surgery for prostate cancer. He has reportedly made a full recovery.