Fairfax County voters embraced mostly mainstream candidates in Tuesday’s Democratic Board of Supervisors primary, nominating veteran politician Jeff C. McKay for board chair after a crowded and vitriolic race energized by calls for a more aggressively liberal government.

McKay (Lee) defeated his closest competitor, Georgetown University law professor Alicia Plerhoples, by double digits, according to unofficial results. School Board member Ryan McElveen was in third place, while developer Tim Chapman — who loaned his campaign $835,000 — trailed far behind.

In November, McKay will be favored over Republican nominee Joe Galdo to become the top elected leader in a solidly blue county of 1.1 million residents, which is confronting a widening gap between the rich and poor, increasingly congested roads and aging infrastructure.

Capturing the nomination to succeed longtime board chair Sharon Bulova (D) was vindication for McKay, an often serious Democrat who was endorsed by Bulova and has served as Lee District supervisor for 11 years.

Winners of the Democratic nominating contests for four other open seats on the 10-member board are: congressional staffer James Walkinshaw (Braddock), former planning commissioner Walter Alcorn (Hunter Mill), county economic development authority marketing director Rodney Lusk (Lee) and School Board member Dalia Palchik (Providence).

McKay, 43, said their victories mean that county voters believe that “experience and a record matters.”

“This is a big, complicated county, and what the voters said tonight is: ‘We’re a strong Democratic county, but we’re also a county that believes in results,’ ” he said.

About 10 percent of voters cast ballots, officials said. Virginia voters don’t register by party.

Chapman accused McKay during the campaign — initially in an anonymously circulated memo — of buying his home through a quid pro quo relationship with two developers, allegations that McKay called “borderline libelous.”

McKay, in turn, hired an attorney who produced a report that rebutted the claims, prompting Chapman to file an ethics complaint with state police.

Voters who supported McKay on Tuesday seemed far more interested in bread-and-butter issues, such as maintaining a fiscally moderate approach at a time when Virginia’s largest jurisdiction is beginning to emerge from a decade of economic austerity triggered by the 2008 recession.

The county’s coffers again are again healthy, but elected officials face increasing demands for affordable homes, increased school spending and actions to protect the environment.

“I think the other candidates had some good ideas, but these guys are working on it right,” Jack Richardson, 73, said about the current leadership after voting for McKay at Langley High School in McLean. “If it ain’t broke, don’t fix it, is I guess what I’m saying.”

Pedro Correa, 65, of Burke, said he admired McKay as co-author of the “One Fairfax” policy, which uses racial and social equity as a prism for spending and planning decisions. “I prefer to vote for somebody who can fight for human rights,” Correa said. “We need people with a feeling of more humanity.”

Other voters applauded calls from McKay’s opponents for more-aggressive stances.

Plerhoples wanted to revisit the idea of a meals tax — which county voters rejected in 2016 — to generate money for affordable housing. She argued that more of the county should be zoned for high-density development.

McElveen proposed building charging stations for electric cars, hiring a chief technology officer and coordinating with telecommunications companies to ensure residents are connected to the growing 5G wireless network. Chapman argued for tightening appeals of commercial property tax assessments and charging developers who build mansions on land zoned for higher density.

For Melissa Dunlap, 50, symbolism played a role in her support for Plerhoples, who would have been the county’s first African American board chairman.

“I like the idea of having a woman of color representing the diversity of Fairfax County,” she said after voting at Lake Braddock Secondary School in Burke. “And, I like her ideas.”

McKay ran as a defender of the county board’s often calibrated approach to governing, touting a record that includes championing a plan to add 13,000 homes, hotels and businesses to a revamped Richmond Highway corridor and the renovation of a once crime-ridden Springfield Town Center.

He said he won’t take anything for granted in the general-election race against Galdo, a former Defense Department technology intelligence analyst who ran for Congress as a Green Party candidate in 2014. But he plans to start meeting with the other Democratic nominees as soon as possible, hoping to map out strategies for addressing key issues once a new board takes office.

“What’s been clear in this primary is that one of the areas that the county can improve upon is environmental stewardship,” McKay said. “Also, we must tackle our affordable housing problem.”

Susan Emerson, 75, said she voted for McKay because she likes his calls to more strictly limit carbon emissions from businesses. “We should be making sure that they preserve open space and parks,” Emerson said. “It all goes toward our quality of life.”

Aaron Wyche, 47, said he is most worried about school funding, which is why he chose Plerhoples — who stressed raising teacher salaries and building more permanent classrooms.

Plerhoples initially planned to run for a School Board seat but dove into the chairman’s race because the other candidates were all white men, she said. She told supporters after conceding Tuesday night that she would remain active in Virginia politics.

The lawyer by training said she believes her candidacy brought more attention to issues such as protecting the environment, expanding prekindergarten and increasing money for affordable housing. She promised to focus on helping Democrats candidates flip the General Assembly, where Republicans hold slim margins in each chamber, and advocating progressive causes through the nonprofit she co-founded, Virginia Democracy Forward.

“First, thank you,” Plerhoples said, standing on a chair to address teary supporters. “We pushed McKay to the left. We got concessions that would not have happened if I didn’t enter the race. I’m very proud of that.”

Plerhoples added: “It’s an amazing, amazing thing that we’ve built. We managed to get this close with just four months of running.”

Harry Pontius, 79, of Burke, said he was inspired to see how much enthusiasm the primary candidates generated in Fairfax, where in recent years it has been much more common for nominees to face little or no competition from within their party.

Still, he said, he supported McKay out of worry that the county board will become too progressive and lose sight of the need to control spending.

“With all the extremes that are happening in U.S. politics today, we need to move back to the mainstream here,” he said.

Rebecca Tan contributed to this report.