Blanket Primary

A blanket primary is a primary-election format that places candidates of all parties on one ballot, allowing each voter to switch parties from race to race — picking, for example, a Republican for governor and a Democrat for senator. The party nominee for the general election is the candidate who wins the most votes within their own party's column.

The format is distinct from:

• a closed primary, where only registered party members may vote in that party's contest;
• an open primary, where any voter may participate but must choose a single party's ballot for all races; and
• a nonpartisan blanket ("top-two" or jungle primary), where all candidates run together and the top two finishers advance regardless of party.

The traditional partisan blanket primary was used for decades in Washington and Alaska, and was adopted by California via Proposition 198 in 1996. The U.S. Supreme Court struck it down in California Democratic Party v. Jones, 530 U.S. 567 (2000), holding that forcing parties to let non-members help select their nominees violated the parties' First Amendment right of association. After Jones, Washington and California migrated to top-two nonpartisan blanket systems (Washington's I-872 in 2004, upheld in Washington State Grange v. Washington State Republican Party, 552 U.S. 442 (2008); California's Proposition 14 in 2010).

Supporters argue blanket and top-two systems boost turnout, weaken partisan gatekeeping, and reward candidates with broader appeal — potentially moderating polarization. Critics counter that they dilute party coherence, enable strategic crossover ("raiding") to nominate weaker opponents, and can produce general elections between two candidates of the same party, leaving minor-party and out-party voters without a meaningful choice in November.

For researchers, the term is sometimes used loosely. Precise usage distinguishes the partisan blanket primary (invalidated in 2000) from the nonpartisan top-two blanket primary now used in California, Washington, and — in a modified four-candidate form — Alaska since 2022.