{ { Infobox election
| election_name = 2018 United States Senate election in California
| country = California
| type = presidential
| ongoing = no
| previous_election = 2012 United States Senate election in California
| previous_year = 2012
| next_election = 2024 United States Senate election in California
| next_year = 2024
| election_date = November 6, 2018
| turnout = 56.42%
| image1 =
| candidate1 = Dianne Feinstein
| party1 = Democratic Party (United States) | popular_vote1 = 6,019,422 | percentage1 = 54.16%| image2 = | candidate2 = Kevin de León | party2 = Democratic Party (United States) | popular_vote2 = 5,093,942 | percentage2 = 45.84% | map_image = | map_size = 250px | map_caption = Feinstein: de León: | title = U.S. Senator | before_election = Dianne Feinstein | before_party = Democratic Party (United States) | after_election = Dianne Feinstein | after_party = Democratic Party (United States) }}
The 2018 United States Senate election in California' took place on November 6, 2018, to elect a member of the United States Senate to represent California, concurrently with other elections to the United States Senate, elections to the United States House of Representatives, and various state and local elections.
Under California's non-partisan blanket primary law, all candidates appear on the same ballot, regardless of party. In the primary, voters may vote for any candidate, regardless of their party affiliation. In the California system, the top two finishers — regardless of party — advance to the general election in November, even if a candidate receives a majority of the votes cast in the primary election. Washington and Louisiana have similar "jungle primary" style processes for U.S. Senate elections, as does Mississippi for U.S. Senate special elections.
The candidate filing deadline was March 8, 2018, and the primary election was held on June 5, 2018.
Four-term Democratic incumbent Dianne Feinstein won re-election in 2012 with 63% of the vote, taking the record for the most popular votes in any U.S. Senate election in history, with 7.86 million votes. Feinstein, at the time, was the ranking member of the Senate Judiciary Committee. She turned 85 years old in 2018, leading some to speculate that she would retire in January 2019, as her long-time colleague Barbara Boxer did in January 2017. However, Feinstein ran for reelection to her fifth full term, winning 44.2% of the vote in the top-two primary; she faced Democratic challenger Kevin de León in the general election, who won 12.1% of the primary vote. For the second time since direct elections to the Senate began after the passage of the Seventeenth Amendment in 1913, no Republican appeared on the general election ballot for U.S. Senate in California. The highest Republican finisher in the primary won only 8.3 percent of the vote, and the 10 Republicans only won 31.2 percent of the vote among them.
In the general election, Feinstein defeated de León by an eight-point margin, 54% to 46%. This was Feinstein's closest election since 1994. Feinstein would not complete this term, dying in September 2023, over a year before it ended.
Candidates
Democratic Party
Declared
Kevin de León, President pro tempore of the California State Senate
Adrienne Nicole Edwards, Vice Chairwoman on the HDT Community Development Foundation board Dianne Feinstein, incumbent U.S. Senator Pat Harris, attorney Alison Hartson, national director of Wolf PAC David Hildebrand, legislative analyst Herbert G. Peters, retired aerospace engineer and candidate for U.S Senate in California in 2016 Douglas Howard Pierce Gerald Plummer Donnie O. Turner, Air Force veteran
Withdrawn
Topher Brennan
John Melendez, television writer and radio personality
Steve Stokes, candidate for the U.S. Senate in 2016
Declined
Ana Kasparian, co-host of The Young Turks Joe Sanberg, entrepreneur and investor
Tom Steyer, hedge fund manager
Cenk Uygur, host of The Young Turks''
Republican Party
Declared
Arun K. Bhumitra, businessman
James P. Bradley, businessman
Jack Crew, bus driver
Erin Cruz, published author
Rocky De La Fuente, entrepreneur and perennial candidate
Jerry Joseph Laws, candidate for the U.S. Senate in 2016
Patrick Little, neo-Nazi and Holocaust denier
Kevin Mottus, candidate for the U.S Senate in 2016
Mario Nabliba, scientist
Tom Palzer, activist, retired city planner and candidate for the U.S. Senate in 2016 Paul Allen Taylor, businessman