Arron O’Dell’s campaign for the Arlington County Board hasn’t been going so well. His social media posts were getting few likes. Audiences at candidate forums didn’t appear to take him seriously. No one was donating to his campaign fund, and he couldn’t afford ads or mailers.

So he took to the sidewalks.

“I am now officially the first politician in Virginia to use spray chalk to make a political campaign sign,” he wrote on Instagram. “It’s cheaper to make $2 for stencil materials cut for free at #arlingtoncentrallibrary and $12 for 2 cans of chalk. Best part is no clean up because it washes away.”

O’Dell, 42, is running against two incumbents and another independent for one of two seats on the five-member County Board.

Democrats Christian Dorsey and Katie Cristol have endorsements, tens of thousands of dollars from donors and the advantages of incumbency and belonging to Arlington’s dominant political party; the other independent, Audrey Clement, has name recognition from a clutch of unsuccessful previous runs for office.

All O’Dell has are his chalked messages, which have faded with recent rains.

“I don’t have the strongest knowledge base and opinions about what people care about,” he said in an interview, positing that this lack of established positions allows him to listen objectively. “This is as much a learning experience as anything for me.”

Dorsey, 47, who holds the board’s rotating chairmanship this year, said voters should decide which of the candidates demonstrate “fitness to solve Arlington’s biggest issues” — housing, infrastructure and the like.

He noted that the board is already grappling with the pending arrival of Amazon and other challenges, a situation that he said makes him better equipped than his lesser-known rivals to spur the creation of affordable housing, come up with a stormwater plan and address other pressing needs.

Cristol, 34, said she and Dorsey have formed a partnership that has improved Arlington’s impact on regional transportation — he through his work on the board of the Washington Metropolitan Area Transit Authority (WMATA), which runs Metro, and she as chair of the Virginia Railway Express.

Cristol said that if control of the Virginia General Assembly goes Democratic on Tuesday, the County Board will be able to push for state laws that would protect the local environment, increase sources of alternative energy and expand child-care capacity, including for children with disabilities or those who need service during non-traditional hours.

The county, which devotes about 5 percent of its budget to affordable housing loans, grants and programs, has been working on initiatives to deal with what is expected to be an influx of residents as Amazon’s hiring of 25,000 or more employees for its Crystal City-Pentagon City hub accelerates over the next decade.

Residents also want elected leaders to ensure the already crowded schools are ready for new students, the transportation system is ready to handle more commuters and the neighborhoods comprising single-family homes do not disappear as more multi-family residences, retail and offices fill up commercial corridors.

That is one of the points made by Clement, who lives in Westover, where garden apartments that historically have been affordable are being redeveloped into higher-cost homes.

“I think there is a general concern about the direction the county is going and lack of attention to the densification of certain parts of the county,” said Clement, 70, who primarily self-funds her campaigns.

She has hit Dorsey for a $10,000 campaign donation he has accepted from the Amalgamated Transit Union and another from the International Brotherhood of Electrical Workers, saying the money should disqualify him from discussions or votes involving labor negotiations.

Dorsey said he has publicly disclosed the donations and has abided by all ethics requirements of WMATA and the county.

“I’ve long been a friend of labor,” he said. “It seems entirely consistent that I’d get support from them. If and when there is a time when I need to recuse myself [from votes or discussions] at Metro, I will.

“I get very disappointed when people think people who work for a living can’t band together and support an elected official. The solution to all this is making sure your interests are fully disclosed, and I’ve done that.”