California Gov. Gavin Newsom made the announcement on Friday.
California state leaders and election officials sounded the alarm after what happened in Wisconsin’s primary where polling places saw long, crowded lines and many voters were concerned about voting in person.
President Donald Trump has dismissed the idea on the grounds that it would hurt Republicans’ electoral prospects, and his re-election team is battling Democratic efforts to expand balloting options.
Physical polling places in California will still be opened.