Former Virginia senator Jim Webb has announced he will make a bid for the White House in 2016, becoming the fourth Democrat to challenge front-runner Hillary Clinton. (Reuters)

Former Virginia senator Jim Webb announced Thursday that he will run for president, setting himself on an uphill trek for the Democratic nomination with little national name recognition and scant financial support.

Webb adds a decidedly more conservative option for Democratic voters in a field in which former secretary of state Hillary Rodham Clinton has tacked to the left under criticism from liberal former Maryland governor Martin O’Malley and socialist Sen. Bernie Sanders (I-Vt.).

Yet Webb is hard to pin down politically. A former Republican who served as secretary of the Navy for Ronald Reagan, Webb talks often of his military service in Vietnam. He is known for an idiosyncratic collection of positions that include opposition to the war in Iraq and advocacy for sentencing reform. An economic populist, he has accused Clinton of coming late to the conversation about excessive chief executive pay, and he has regularly championed the plight of rural and working-class Americans.

One of his central challenges will be to parlay those credentials into support among an increasingly liberal Democratic primary electorate.

Also uncertain is whether Webb can appeal to women, a crucial constituency that could be difficult to win over given his past opposition to letting women serve in combat.

Former Navy secretary and Virginia senator Jim Webb is a Democratic contender for the White House in 2016. Here's his take on Obamacare, his issues with the Democratic party, and more, in his own words. (Julie Percha/The Washington Post)

As an often prickly iconoclast who chafes at the demands of the campaign trail — and who has openly doubted whether he could raise the necessary money to run for president — Webb also must demonstrate that he can build a viable presidential campaign operation.

In an announcement message that ran over 2,000 words on his campaign Web site (which crashed for more than an hour after its release Thursday), Webb presented his differences with the rest of the field as his signature strength.

“I understand the odds, particularly in today’s political climate where fair debate is so often drowned out by huge sums of money,” he said. “Let’s clean out the manure-filled stables of a political system that has become characterized by greed.”

In the announcement, Webb mixed his policy goals with his personal narrative — and dwelled far more than his rivals on national security.

Reminding voters that he has spent his “entire life in and around the American military,” the former Marine reiterated his early and passionate opposition to the war in Iraq, his subsequent opposition to intervention in Libya and his concern about ongoing negotiations with Iran. He promised not to allow Chinese territorial expansion and cyberattacks.

“We need a President who understands leadership, who has a proven record of actual accomplishments, who can bring about bipartisan solutions, who can bring people from both sides to the table to get things done,” Webb said in an e-mail to supporters.

As his Democratic rivals have, Webb called for investment in infrastructure and early childhood education as well as reform in the areas of immigration, student debt and criminal justice. He was an early advocate of overhauling the American prison system; earlier this week he said that drug addiction should be treated as a medical rather than criminal concern. He called for a return to “true economic fairness” through changes in tax and labor policy.

Many of his positions place him squarely to the right of his Democratic rivals.

He has accused fellow Democrats of using low-income white men as a “whipping post” and argued against broad affirmative action and diversity programs. Just this month, he defended those who retain fondness for the Confederate flag. He opposes any increase in income taxes while supporting capital gains tax increases. He was critical of Obamacare, though he voted for it. He advocates for gun rights and against coal plant regulations.

While several presidential contenders have professed indecision about their plans merely as a way to keep raising unlimited funds, for months Webb appeared genuinely undecided.

He has made stops in early primary states, but not nearly as consistently as his top rivals. And already, he has experienced campaign turmoil, with two top staffers leaving his campaign in Iowa, the only state where he has an operation.

Also, his political action committee has come under scrutiny for paying out $90,000 to his wife and daughter for Web site design and management. A spokesman defended the payments as legitimate.

“Jim feels pretty strongly about trying to do it differently, and unfortunately the process is bigger than any one individual,” said a friend who preferred not to speak publicly of Webb’s political chances.

But Webb likes to remind skeptics that he’s beaten long odds before. He launched his Senate campaign nine months before the general election. He went on to unseat Republican George Allen by less than 1 percent of the vote, buoyed by an unusual racial slur used by his opponent at a rally.

The victory helped Democrats take control of the Senate. But in 2011, Webb announced that he would not seek reelection.He made no secret of his frustration with the Senate’s sluggish pace or his distaste for campaign obligations. He was often a vocal critic of his own party and its priorities.

He was also sharp-tongued with political opponents, once coldly dismissing a friendly question from then-President George W. Bush about his son serving in Iraq.

Despite his political ambivalence, Webb’s six years in office were not without accomplishments. Webb passed a post-Sept. 11 GI Bill and helped establish a wartime contracting commission that found that tens of billions of dollars had been wasted in Iraq and Afghanistan. He was influential in the government’s pivot toward Asia.

Some of the issues he failed to win support for in the Senate have found broader support since he left.

Webb pushed unsuccessfully for congressional authorization of continued military action in Libya. His successor, Democrat Timothy M. Kaine, has taken up that cause in the battle against the Islamic State. The administration is currently negotiating with lawmakers over a new authorization of use of force. Years after his bipartisan commission to review the nation’s sprawling criminal justice system was blocked by Republicans, conservatives have embraced a sentencing overhaul.

Both Kaine and Mark R. Warner, Virginia’s other senator, have endorsed Clinton.

Webb is the fifth Democratic candidate to enter the presidential race, joining Clinton, O’Malley, Sanders and former Rhode Island governor Lincoln Chafee.

A self-described “solo practitioner” for half his life, the former war journalist and novelist now faces a grueling campaign slog.

Polls find that low-income whites would prefer almost any Republican nominee to Clinton, suggesting a possible opening for Webb. Yet in his 2006 Senate campaign, Webb did not fare any better than other Democrats with white men. He lost that demographic by 24 points in 2006; Virginia Gov. Terry McAuliffe (D), running a more liberal-oriented campaign, lost them by 25 points in 2013. While he fared better than subsequent Democratic candidates among Virginia’s rural voters, he still relied on Northern Virginia and urban centers to win his Senate race.