Top-two primaries: why a California ballot can list two candidates from one party
California uses a single-ballot primary where all candidates compete together and the top two advance to the general election.
California's primary election system is fundamentally different from most of the country. Instead of separate party primaries where Republicans choose Republican nominees and Democrats choose Democratic nominees, California holds a single primary election where all candidates for the same office appear on the same ballot. The top two candidates who receive the most votes—regardless of their party affiliation—advance to the November general election.
This system, known as the top-two primary, has shaped California politics since 2012. It can produce general elections where two candidates come from the same party, or where no candidate from a major party survives to face the general election. For candidates, it means running statewide campaigns in a crowded primary field where party affiliation alone does not guarantee a path to November. For voters, it means choosing from all candidates at once rather than staying within party lines during the primary.
The top-two system emerged from California's constitutional struggles with how to structure its primary elections. Before 2012, California used a blanket primary system that allowed voters to pick one candidate per office without regard to party lines—a voter could select a Democrat for Senate and a Republican for Assembly on the same ballot. However, the U.S. Supreme Court struck down that blanket primary in 2000, ruling it violated political parties' constitutional rights. The top-two system that followed was designed to preserve broad voter participation while respecting parties' right to control nominee selection.
The Constitutional History Behind the System
California's blanket primary system, used before 2012, allowed voters unprecedented flexibility: "pick one candidate for each office without regard to party lines." This meant a single voter could support candidates from different parties in the same election. The system offered broader voter choice than closed primaries, which restrict voting to registered party members only.
However, the U.S. Supreme Court ruled California's blanket primary unconstitutional in 2000 in the case *California Democratic Party v. Jones*. The Court decided 7-2 that the system violated political parties' First Amendment right of association. Justice Antonin Scalia, writing for the majority, articulated the core constitutional problem: "Proposition 198 forces political parties to associate with—to have their nominees, and hence their positions, determined by—those who, at best, have refused to affiliate with the party, and, at worst, have expressly affiliated with a rival."
The Court found that allowing non-party members to select a party's nominees was a violation of the party's "basic function" to choose its own leaders. Scalia warned that "a single election in which the party nominee is selected by nonparty members could be enough to destroy the party." The Court essentially prioritized political parties' constitutional rights over California's interest in broadening voter participation in primaries. This left California needing a new system.
California adopted Proposition 14 in response, which passed on the June 2010 ballot with 53.7 percent of the vote. The measure was designed to maintain a system somewhat similar in spirit to the blanket primary—allowing all voters to participate in one primary election—while passing constitutional scrutiny by allowing parties to maintain associational control. The top-two system took effect for the 2012 election cycle.
Understanding the Ballot
On a California primary ballot, all candidates for the same office appear together on one ballot. Each candidate's name is listed alongside their indicated party preference. Candidates indicate their party preference on the ballot, though this is merely a preference statement rather than an official party endorsement. A candidate can claim affiliation with a party even if that party has not officially endorsed them, and voters can see all options before making a choice.
Because all candidates run on the same ballot in the primary, races can become crowded. A Senate race might feature ten candidates: five Democrats, three Republicans, two from other parties or unaffiliated. All ten compete simultaneously for votes on the same ballot, and voters select a single candidate. The two candidates who receive the most votes, combined across all party lines, advance to November. The primary election thus determines who appears in the general election, not a party organization or internal party process.
This differs from closed primary systems, where only registered party members vote in their party's primary. In a closed primary, the Republican primary produces a Republican nominee through votes only from registered Republicans, and the Democratic primary produces a Democratic nominee through votes only from registered Democrats. California's system eliminates this party-controlled gatekeeping and makes the primary itself the broad public election.
When Two Candidates From the Same Party Advance
One consequence of the top-two system is that both advancing candidates can come from the same political party. In the 2012 election, eight congressional districts featured general elections with two candidates of the same party. Six of these districts had two Democrats advancing to the general election, while two had two Republicans. This pattern has continued in subsequent elections.
In these races, the general election matchup is determined entirely by the primary. Voters in the general election face a choice between two candidates from the same party, with no option to vote for the other major party's nominee. Voters who prefer the other party have no partisan option on their ballot in November. The general election becomes a choice within a single party rather than a choice between parties.
This structure differs fundamentally from traditional partisan primaries. In those systems, the Republican primary produces a Republican nominee and the Democratic primary produces a Democratic nominee, ensuring that the general election offers a choice between the parties. Under California's system, a district can elect two Democrats to advance if both receive more votes than any Republican or independent candidate, even if Republicans tried to compete in the primary. The outcome depends entirely on which candidates get the most votes, not on party affiliation.
“The Court found that allowing non-party members to select a party's nominees was a violation of the party's basic function to choose its own leaders.”
Which Elections Use the Top-Two System
California's top-two primary applies to races for federal and state offices. This includes U.S. Senators, Congressional Representatives, State Senators, Assemblymembers, Governor, Lieutenant Governor, State Treasurer, Secretary of State, State Attorney General, and other statewide executive positions. Voters in California experience the top-two system when voting in these races in their primary elections.
The system does not apply to presidential primaries, which remain party-based in California as they are nationwide. In presidential elections, California still holds separate Democratic and Republican primaries where voters choose among candidates competing for each party's nomination. The top-two system also does not apply to local offices such as city council or county positions, or to nonpartisan positions such as judgeships. Those races use other primary or selection systems determined by state law and local ordinance.
How the System Affects Candidates
For candidates, the top-two primary system means building a campaign that appeals beyond party lines, or at minimum finishing in the top two among a potentially large field. A candidate cannot rely solely on consolidating support within their party and then facing the other party's nominee in a two-person race. Instead, every candidate must compete directly against all other candidates, regardless of party affiliation.
In a crowded primary field, vote totals can be lower than in traditional two-party contests. A candidate might win a top-two primary with 25 or 30 percent of the vote if the field is sufficiently split across multiple candidates. This incentive structure encourages candidates to build coalitions that cross party lines or appeal to voters who are unaffiliated with either major party. A candidate's path to victory depends on vote-getting ability in a wide field, not on controlling a party's nomination process.
Candidates also must consider their positioning relative to likely competitors. In a race where multiple candidates from their party may run, they need to differentiate themselves to finish in the top two. In districts where one party is dominant, candidates from the minority party know they face steep odds of advancing. This affects who decides to run and how they campaign. Some candidates from the trailing party may choose not to run, or may focus on building a personal brand that transcends party affiliation.
