California's 4th Congressional District (CA-4)

Last updated Oct 1, 2026 · 6 sources

Mike Thompson, a Democrat, has represented the district since 2023.

The district includes all of Lake and Napa counties and parts of Yolo, Solano, and Sonoma counties.

According to the Census Bureau's 2020–2024 American Community Survey 5-year estimates, the district has a population of 764,257, a median household income of $97,540, and a median age of 39.3. Of residents 25 and older, 36.2% hold a bachelor's degree or higher.

Representative

Mike Thompson

U.S. Representative for California's 4th District · Democrat

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2026 redistricting

California uses a new congressional map in 2026: AB 604 (Proposition 50), approved by voters Nov 4, 2025.

The 2026 election for CA-4 uses the new map's CA-4; the map on this page shows the district as currently drawn (119th Congress).

Source · All 2026 redistricting changes

2026 election

Thompson has filed with the FEC to run for this seat in 2026. 8 candidates for the seat have reported receipts to the FEC.

8 candidates have reported raising money for the 2026 CA-4 race to the FEC.

Election Day: Tuesday, November 3, 2026

Candidates for CA-4 in 2026 who reported raising money to the FEC
Candidate	Party	Raised	Cash on hand	Through
Eric Jones	Democratic	$8,378,929	$655,718	Jun 30
Mike Thompson (incumbent)	Democratic	$4,204,013	$1,075,737	Jun 30
Raymond Riehle	Republican	$114,861	$4,242	Jun 30
Laurie John Mackenzie	Republican	$14,129	$8,084	Jun 30
Sharon Brown	Republican	$7,000	$0	Jun 25
Mandy Ghusar	Republican	$7,000	$0	Jun 20
Trevor Merrell	Democratic	$6,435	-$24	Mar 31
John Wesley Tyler	Independent	$1,385	$0	Jul 16