Review note: John Carli for Solano County Supervisor District 4 -- his own campaign site's "About" page and Michael Silva for Solano County Supervisor D4 -- his own campaign site may have more bias because they are advocacy voter guides compared to other formal government and nonprofit journalism sources.
- content.solanocounty.gov (opens in a new tab)Solano County Registrar of Voters -- official "Candidate Filed Log - November 3, 2026 General Election" (as of 8/20/2026): the only county-section contests are Board of Supervisors District 4 (Michael Silva, John Carli) and County Board of Education Trustee Area 6 (Tamika Hamilton, Kathryn Kedarisetty) -- Trustee Areas 3 and 4 each drew a single incumbent filer and are marked "OFF THE BALLOT"; no Assessor, Auditor-Controller, Sheriff, District Attorney, Clerk-Recorder, Treasurer-Tax Collector, Public Defender, or Superior Court judge section appears anywhere in the document
- solanocounty.gov (opens in a new tab)Solano County -- its own "Board of Supervisors" page: confirms the board's 5-member, 5-district structure (Cassandra James D1, Monica Brown D2, Wanda Williams D3, John M. Vasquez D4, Mitch Mashburn D5) and the board's powers (annual budget, county ordinances, appointments to most non-elected county offices)
- dailyrepublic.com (opens in a new tab)Daily Republic -- "Silva takes early, narrow lead for District 4 supervisor" (Todd R. Hansen, June 3, 2026): the Registrar of Voters' first-count results for the June 2, 2026 primary -- Silva 4,231 votes (43.78%), Carli 3,553 (36.76%), Juan Desmarais 1,881 votes -- explicitly an early, not-yet-certified count. The article's own reported Desmarais share (18.46%) does not match votes/total (9,665); this dataset uses the recomputed 19.46%. Names Silva as Vacaville's vice mayor and a professor, Carli as the former Vacaville police chief and sitting mayor, and Desmarais as a Vacaville barbershop owner; reports that six-term incumbent John Vasquez ended his campaign for health reasons and endorsed Carli
- dailyrepublic.com (opens in a new tab)Daily Republic -- "Silva only District 4 candidate to speak on issues" (Daily Republic Staff, May 17, 2026, updated May 18): independently corroborates all three June primary candidates' names (Silva, Carli, Desmarais) and that questions were sent to Carli at his email on record with the Solano County Registrar of Voters and to Desmarais at his own provided email; publishes Silva's own answers on the county's fiscal pressures, unchecked development in District 4, and the California Forever Suisun City expansion project
- carliforsolano.com (opens in a new tab)John Carli for Solano County Supervisor District 4 -- his own campaign site's "About" page: his own biography (born 1966 in Petaluma, adopted as a child, 35 years in public service, Vacaville police officer since 1989, Chief of Police, elected Mayor of Vacaville 2023-2026) and his own platform statements on water, economic development, transportation, public safety, housing, Travis Air Force Base, and countywide tax-sharing after the county rescinded its property-tax-sharing agreement in Aug. 2024
- silvaforsolano.com (opens in a new tab)Michael Silva for Solano County Supervisor D4 -- his own campaign site: his own biography (EdD, Vacaville City Councilmember, biotechnology professor, lifelong Solano County resident) and platform (protecting agriculture and open space, expanding economic opportunity, "people-first leadership")
- cal-access.sos.ca.gov (opens in a new tab)California Secretary of State CAL-ACCESS -- "CARLI FOR SOLANO COUNTY SUPERVISOR DISTRICT 4 2026; JOHN" (Filer #1487921), status ACTIVE -- no Form 460/461/450 electronically filed for the 2025-2026 cycle as of this retrieval
- cal-access.sos.ca.gov (opens in a new tab)California Secretary of State CAL-ACCESS -- "SILVA FOR SOLANO COUNTY SUPERVISOR DISTRICT 4 2026" (Filer #1486202), status ACTIVE -- no Form 460/461/450 electronically filed for the 2025-2026 cycle as of this retrieval
Last updated September 7, 2026.
County
Solano County Board of Supervisors, District 4
This person is one of five supervisors who govern Solano County. They vote on the yearly budget and county laws. They also decide land use and services in the unincorporated county. They appoint people to most county offices that aren't elected. The term is four years.
Solano County's District 4 supervisor race is an open two-person contest. Six-term incumbent John Vasquez quit the race for health reasons and backed Mayor John Carli. Carli faces Vice Mayor Michael Silva on November 3.
The winner serves a 4-year term on the county's 5-member Board of Supervisors. The board adopts Solano's annual budget and ordinances. It sets land-use policy for the unincorporated county. It also confirms appointments to most non-elected county offices. District 4 covers Vacaville and Dixon. Supervisors also represent the county on regional bodies like the Solano Transportation Authority.
The choice weighs continuity against a fresh face on the same council. Carli argues that his 35 years in Vacaville government are ready to scale up to the whole county. That record is capped by a term as mayor. He also carries the outgoing supervisor's endorsement. Silva argues that the county's budget pressures call for his outside expertise in organizational change. He was the only primary candidate willing to detail his views to local reporters before the vote.
Michael Silva
Michael Silva is Vacaville's vice mayor and a biotechnology professor. He wants to restructure county services to close a budget gap from federal cuts. He led the June 2 primary with 43.78% of the vote.
John Carli
John Carli is Vacaville's mayor, a retired police chief, and Vasquez's endorsed choice. He runs on his City Hall record, which includes a $4.4 million public-safety grant. He finished second in the June 2 primary with 36.76%.
Your pick
A nonpartisan office: candidates do not run as Democrats or Republicans, and no party appears on the ballot.