Christian Dorsey, left, and Katie Cristol, candidates for Arlington County Board. ( Courtesy of Christian Dorsey (left); Photo by Emily Goodstein (right))

ARLINGTON COUNTY, for years an almost unalloyed success story, has hit a patch of unfamiliar self-doubt. Sequestration and the effects of slower federal spending have driven up office vacancies, sapping tax revenue; at the same time, the county’s budget is under intense pressure from soaring school enrollment and demands for increasingly scarce affordable housing.

One result has been a year of political upheaval in a locality of 230,000 people long accustomed to consensus. The contentiousness has bled into the races for the county board, on which, owing to the retirements of a pair of long-serving members, two of the five seats are open for the first time in three decades. The elections are Nov. 3.

Four well-qualified candidates are running for those two seats. The best are a pair of Democrats: Katie Cristol, an impressively smart and committed education policy expert, and Christian Dorsey, a think-tank executive who is broadly knowledgeable about housing and community development.

Ms. Cristol is a first-time candidate whose energy, focus and analytic skills helped her to a first-place finish in the party primaries in June. She’s maintained a strong campaign in the general election, staking out clear and balanced positions on creating more affordable housing, which she favors, and expanding tax breaks for developers and businesses, which she opposes. In a county that has undergone rapid change, she is representative of a new wave of Arlingtonians — young, highly educated and attuned to the aspirations of young single residents and families, as well as immigrants, trying to make a life there.

Mr. Dorsey, director of external and government affairs at the Economic Policy Institute, has run a similarly constructive campaign, offering proposals to encourage home energy efficiency and to revitalize the county’s ample stock of aging retail businesses. His career path has included stints promoting literacy for indigent children, and he has extensive volunteer experience in the county. He’d make a fine board member.

The other two candidates, both running as independents, are Audrey Clement, formerly of the Green Party; and Mike McMenamin, who has been endorsed by the county Republican Party. Ms. Clement, a civic activist, is a perennial candidate for the board. Mr. McMenamin, a lawyer and recent president of the Arlington Civic Federation, has also run previously for the board.

Both are serious candidates and have attacked what they consider Arlington’s profligate spending generally, and, in particular, the county’s ambitious plan to develop more affordable housing. Yet neither has advanced convincing proposals to trim spending or explained why enlarging the stock of affordable housing should not be a priority in a place where the supply of it has diminished rapidly with gentrification.