There has been much discussion about whether votes in this next election will be counted securely.
Every state has rules about what poll observers can do at the polls and how votes can be challenged. Here are the rules for your state:
California See Elections Observation Rights and Responsibilities, California Office of Secretary of State.
On the day of the election no person, other than a member of a precinct board or other official responsible for the conduct of the election, shall challenge or question any voter concerning the voter's qualifications to vote. (California Elections Code Ann. § 14240).