(CNN) Nearly half a million California voters may be unable to participate in the state's presidential primaries on June 7 as a result of confusion in the voter registration process, a Los Angeles Times investigation has discovered.

Hundreds of thousands of Californians who intended to register as independents may have accidentally registered instead with the ultra-conservative American Independent Party (AIP), which opposes abortion rights and same-sex marriage, and calls for building a fence along the entire U.S. border.

The LA Times reports that "a majority of (AIP) members have registered with the party in error," and that "nearly 3-in-4 people did not realize they had joined the party" after surveying registered members.

The Times had a team of Republican and Democratic pollsters contact a list of 500 AIP members, obtained through a public records request, who determined that "fewer than 4% could correctly identify their own registration as a member of the American Independent Party."

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Many of those contacted were confused by the inclusion of the term "independent" in the party's name, and thought they had registered as independent voters with no party affiliation -- which would have allowed them to participate in the state's Democratic primary, unlike AIP voters.

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