2020Final results
2020 election for California's 42nd District
U.S. House · California
Ken Calvert (R) won with 57.1% of the vote, defeating William "liam" O'Mara (D) by 14.3 points.
Ken CalvertRepublican · winner
57.1%210,274
William "liam" O'MaraDemocrat
42.9%157,773
368,047 votes
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 10:09 AM ET
The seat over time
D − R margin in this seat's races around 2020
Races before and after
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 10:09 AM ET
Money in this race
Each line compares the two campaigns on one scale.
William "liam" O'MaraKen Calvert
$131.4K
Raised by the campaign
$1.4M
$130.1K
Spent by the campaign
$1.6M
$1.3K
Cash on hand
$410.6K
Campaign money: FEC, through Dec 31, 2020.
Source: FEC campaign filingsUpdated Dec 31, 2020