Vietnam veteran and former US Senator Jim Webb has launched his bid for president, joining other Democrats taking on front-runner Hillary Clinton.
Mr Webb, 69, who represented Virginia from 2007 to 2012, said the US needed “positive, visionary leadership”.
He said defence, criminal justice reform and an economy that benefits the middle class would be his focus.
He is the fifth Democrat to enter the presidential race. There are 14 Republican challengers so far.
In a statement on his campaign website, Mr Webb said he made the decision to run “after many months of thought, deliberation and discussion.”
“I understand the odds, particularly in today’s political climate where fair debate is so often drowned out by huge sums of money,” he added.
Vowing to bring an outsider’s voice to the 2016 race, he said the US needed “to shake the hold of these shadow elites on our political process”.
Mr Webb was a vocal critic of the Iraq war, which his son served in, and his opposition formed the basis of his Senate election campaign in 2006.
Prior to becoming a senator, he worked as an author and film-maker and briefly served as US Secretary of the Navy under Ronald Reagan, but resigned in protest at cuts to the military.
Latest polls suggest Mr Webb is a long way behind the levels of support seen for Hillary Clinton and her closest Democratic challenger, Bernie Sanders.
Analysis: Anthony Zurcher,
The afternoon before a major national holiday is usually a time for releasing bad or unflattering news, not announcing presidential candidacies. That didn’t stop Jim Webb from unveiling his bid for the White House via email and his campaign website, however – and given his penchant for unpredictability, it somehow seems fitting.
Despite the record number of big-name candidates in the 2016 presidential race, none has a resume quite as unconventional as Mr Webb. The Virginian seeks to provide a rough-hewn, working man’s appeal that contrasts sharply with Democratic front-runner Hillary Clinton’s carefully planned, big-money candidacy.
The National Journal’s Bob Moser once described Mr Webb’s politics as combining “Elizabeth Warren’s passion for economic justice with Rand Paul’s itch to reinvent foreign policy”.
So far, polls show Democratic voters with little interest in such an unusual blend. But even if he fails to gain traction in the race, Mr Webb should be fun to watch.
Declared presidential candidates
- Hillary Clinton, former First Lady and Secretary of State
- Martin O’Malley, former governor of Maryland and mayor of Baltimore
- Bernie Sanders, independent senator from Vermont, caucuses with the Democrats
- Lincoln Chafee, former senator and governor of Rhode Island
- Jim Webb, former senator and Vietnam veteran
- Jeb Bush, former Florida Governor
- Ted Cruz, Texas senator and conservative firebrand
- Rick Santorum, Christian conservative from Pennsylvania
- Marco Rubio, Florida senator since 2011
- George Pataki, former three-term governor of New York
- Ben Carson, author and neurosurgeon
- Carly Fiorina, former boss of Hewlett Packard
- Mike Huckabee, former governor of Arkansas
- Rand Paul, libertarian conservative Kentucky senator
- Lindsey Graham, South Carolina senator since 2003
- Rick Perry, former Texas governor
- Donald Trump, celebrity property mogul
- Bobby Jindal, governor of Louisiana
- Chris Christie, governor of New Jersey