Nearly 120,000 names were left off the voting rolls in Los Angeles during Tuesday's crucial jungle primary due to a printing error, local officials said.
The 118,522 voters' names were erroneously excluded across more than a thousand precincts in the state, local officials said.
"We apologize for the inconvenience and concern this has caused," Dean C. Logan, the county clerk, said in a statement. "Voters should be assured their vote will be counted."
The local registrar's office has said registered voters who have been affected by the printing error can cast provisional ballots that will be counted, Los Angeles' KTLA reported.
But former Los Angeles mayor Antonio Villaraigosa, who is locked in a fierce primary fight for the number-two spot in the California gubernatorial race, called for polls to remain open longer as a result of the snafu.
"I'm calling on @LACountyRRCC to keep the polls open longer because of the unprecedented number of voters left off the voter rolls," Villaraigosa wrote on Twitter. "You have the right to vote. If you were turned away, return to your polling place & exercise your right to vote by requesting a provisional ballot."
Los Angeles County Democratic Party Chair Mark Gonzalez said in a statement that many voters probably will be too frustrated to take the city up on that offer, though.
"While it is true that voters whose names are not on their precinct's voter roll can and must obtain that provisional ballot to cast their vote, it is an inevitability that many will have seen their names not on the voter roll and be turned off from voting entirely," Gonzalez said.
"We will work closely with Dean Logan and the County Registrar to ensure this does not happen again and that every vote is counted," he added.
Newsom is the clear front-runner in the race.
Because of California's "jungle primary ," the top two vote-getters -- regardless of party -- advance to a runoff in November.
Newsom has said he would prefer to face a Republican and it's understandable because Democrats dominate in California. Republican registration has fallen for years and the party has not won a statewide contest in more than a decade, when Arnold Schwarzenegger was re-elected governor in 2006.
The Associated Press contributed to this report