Gephardt has risen through party ranks to become a Democrat grandee with a strong network of allies. He began 2004 with more endorsements from Democrat representatives than any of his rivals.
A champion of organised labour who strongly promotes universal healthcare, the former House majority leader has long held ambitions to become president – a previous attempt for selection as the Democrat's presidential challenger failed in 1988.
But after nearly 27 years in the House of Representatives, Gephardt believes he has honed and polished the image and ideas needed to win the presidency.
Born and raised in St Louis, Missouri, Richard Andrew Gephardt graduated with a law degree from the University of Michigan in 1965 and worked as a lawyer until 1971.
Age: 63 on 31 January
Spouse: Jane Byrnes Gephardt
Current post: Congressman, Missouri (since 1976)
Military record: Missouri Air National Guard (1965-1971)
He entered Congress representing a St Louis-based constituency in 1976. Rising rapidly through the ranks, Gephardt was elected chairman of the Democrat caucus in the House of Representatives from 1984 and became majority leader in 1989.
In the mid-1980s, he also helped found the Democratic Leadership Council, which advocated a pragmatic centre-right course that Bill Clinton adopted with great success.
But Gephardt later parted company with the DLC over his pet issue of trade. He also shifted certain conservative views, such as his anti-abortion stance, in a more liberal direction.
After the Republicans took control of the House in 1994, Gephardt was elected minority leader and led the caucus through four unsuccessful attempts to regain control. He resigned as minority leader in 2002, to focus his efforts on running for president.
Gephardt has based his bid on one big idea: universal healthcare. His plan rests on tax credits to fund at least 60% of the cost of health coverage for workers and would cover 97% of Americans, he says.
It is a potentially vote-winning idea – but would reportedly cost at least $250 billion a year. His readiness to repeal tax cuts to pay for it may sound too scary for many Americans.
Gephardt has also accused the Bush administration of abusing civil liberties in its drive for domestic security, and says he would fire its architect, Attorney General John Ashcroft, in his "first five seconds as president".
Gephardt backed President Bush on the issue of regime change in Iraq before the invasion and continued to insist afterwards that weapons of mass destruction would be found.
After July 2003, he began to criticise Bush's handling of the affair, saying the president should have worked more closely with allies instead of resorting to "chest-beating unilateralism". But Gephardt continues to back the war.
Union-friendly Gephardt sees minimally regulated "free trade" as a threat to US workers and environmental standards. To counter this effect, he argues for protective measures such as a variable international minimum wage, tailored to countries' level of development.
Gephardt (R) must see off rivals
such as Senator John Edwards
He has also been sharpening his ideas by conferring with former Defence Secretary William Perry about North Korea and diplomat Dennis Ross about the Middle East. Gephardt is a firm supporter of Israel.
But Gephardt has made his mind up about one Arab Gulf monarchy at least, saying: "This administration needs to stop behaving like the United States of Saudi Arabia and it needs to start mobilising international pressure to get Saudi Arabia to stop funding, training and breeding global terror in the first place."
"We’re recognising Gephardt because he’s loyal, he’s stood with working people for years and because he believes that if you work hard, you deserve healthcare coverage with your employer providing it."
- United Food and Commercial Workers union.
"Why in the world would Americans want to keep an ineffective leader in Washington, let alone promote him to the White House?"
- Jeani Murray, Howard Dean's Iowa campaign director.
Gephardt strength, his experience, is also his weakness. Critics say he is a dull, Washington insider with nothing fresh to offer.
Worse, some say, he is tainted by decades of compromises and policy shifts, with his support for Bush's war on Iraq symbolic of what is wrong with the Democrat party.