Jim Webb has announced he will no longer seek the 2016 Democratic presidential nomination.
The former Virginia senator has said on October 20 that he is considering how he might “remain as a voice” in the campaign, possibly as an independent candidate.
Jim Webb has struggled to gain traction in the Democratic primary, often polling at or below 1%.
Ex-Secretary of State Hillary Clinton is still leading the race, followed by Vermont Senator Bernie Sanders.
“I am withdrawing from any consideration of being the Democratic Party’s nominee for the presidency,” Jim Webb said.
“This does not reduce in any way my concerns for the challenges facing the country … or my intentions to remain fully engaged in the debates that are facing us.”
Jim Webb, who was a Navy secretary under Republican President Ronald Reagan, became a Democrat after opposing the Iraq War.
During the first Democratic debate, Jim Webb struggled to explain why he was at odds with his party on key issues like gun control and affirmative action.
He also often complained about his lack of speaking time.
Jim Webb had been promoting criminal justice reform and an overhaul of campaign finance laws while criticizing President Barack Obama’s foreign policy.
Former senator Jim Webb has launched his bid for president, joining other Democrats taking on front-runner Hillary Clinton.
Jim Webb, who represented Virginia from 2007 to 2012, said the US needed “positive, visionary leadership”.
The 69-year-old Vietnam veteran said defense, criminal justice reform and an economy that benefits the middle class would be his focus.
Jim Webb is the fifth Democrat to enter the presidential race. There are 14 Republican challengers so far.
In a statement on his campaign website, Jim 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, Jim Webb said the US needed “to shake the hold of these shadow elites on our political process”.
Jim 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 Jim Webb is a long way behind the levels of support seen for Hillary Clinton and her closest Democratic challenger, Bernie Sanders.