The blanket primary is a system used for selecting political party candidates in a primary election in the United States. In a blanket primary, voters may pick one candidate for each office without regard to party lines; for instance, a voter might select a Democratic candidate for governor and a Republican candidate for senator. In a traditional blanket primary the candidates with the highest number of votes for each office in each party advance to the general election, as the respective party's nominee. Blanket primaries differ from open primaries – in open primaries voters may pick candidates regardless of their own party registration, but may only choose among candidates from a single party of the voter's choice. A blanket primary gives registered voters maximum choice in selecting candidates.
Compared to other primary systems, the blanket primary is less restrictive for voters because it does not limit them to selecting from only one party's candidates. Mainstream political parties, however, may see this as a disadvantage because it discourages party loyalty, especially among moderate voters who do not identify strongly with either party. The system also has potential for tactical voting: Voters opposed to one party might disingenuously choose a weaker candidate from that party, setting the candidate up to lose in the general election.
In 2000 the Supreme Court of the United States struck down California's blanket primary in California Democratic Party v. Jones. Similar systems used by Washington and Alaska were also struck down in subsequent Supreme Court cases.
In response to the aforementioned Supreme Court decision, Washington state voters passed Initiative 872 in 2004 to adopt the Louisiana-style nonpartisan blanket primary; while lower courts, following the ruling in California Democratic Party v. Jones, struck down the initiative, the Supreme Court ruled on March 18, 2008 in Washington State Grange v. Washington State Republican Party et al. that Initiative 872 was at least facially constitutional and could go into effect.
- Asseo, Laurie (June 26, 2000). "Court nixes 'blanket' primaries". Salon.com.
- "Washington State Grange v. Washington State Republican Party et al." (PDF). March 18, 2008.