1990Flipped from RepublicanFinal resultsIncumbent defeated
1990 election for California Senate District 4
California State Senate · California
Mike Thompson (D) won with 47.7% of the vote, defeating James W. Nielsen (R) by 1.0 points, a seat Republicans won last time.
Mike ThompsonDemocrat · winner
47.7%125,573
James W. NielsenRepublican · incumbent
46.7%123,066
Juanita A. HendricksLibertarian
3.6%9,398
Irv SutleyPeace and Freedom
2.0%5,381
263,418 votes
Source: Harvard Dataverse / Carl KlarnerUpdated Sep 30, 2026, 7:29 AM ET
The seat over time
D − R margin in this seat's races around 1990
Races before and after
Source: Harvard Dataverse / Carl KlarnerUpdated Sep 30, 2026, 7:29 AM ET
The candidates
Mike Thompson (D)James W. Nielsen (R)
Also on the ballot: Juanita A. Hendricks (Libertarian), 3.6%; Irv Sutley (Peace and Freedom), 2.0%