Poll managers, any voter, and any qualified watcher may challenge the vote of a person who may be known or suspected not to be a qualified voter. A challenge may also be made if you have good reason to believe the person has already voted or has become disqualified.
Challenges of ballots cast in person in the absentee precinct and at the polling place on election day must be made prior to the voter casting the ballot. No challenges can be made after that time. All challenges must be addressed to poll managers and not directly to voters.
Challenges of absentee by mail ballots must be made prior to separating the ballot from absentee return envelope, which can begin as early as 9:00 am on the day preceding the election.
If a challenged voter casts a provisional ballot, the challenger must appear or produce evidence at the provisional ballot hearing to sustain the challenge; otherwise, the ballot will be counted.
See S.C. Code sections 7-13-810 and 7-13-830.