The episode is one of many warning signs that has election officials on alert as voting begins for midterm elections, the biggest test of the American election system since Mr. Trump’s lies about the 2020 results launched an assault on the democratic process.
In the two years since, groups of right-wing activists have banded together, spreading false claims of widespread fraud and misconduct in elections. Now those activists are inserting themselves in the vote count, with a broad and aggressive effort to monitor voting in search of evidence that confirms their theories.
Many of the activists have been mobilized by some of the same people who tried to overturn Mr. Trump’s defeat in 2020.
Their tactics in primary elections have officials braced for a range of new challenges, including disruptive poll watchers and workers, aggressive litigation strategies, voter and ballot challenges and vigilante searches for fraud.
Both Republican and Democratic election officials say the efforts are unlikely to cause widespread disorder or disruptions. They are prepared to accurately count the tens of millions of votes expected to be cast in the coming weeks, they said. But episodes such as the one in South Carolina come with consequences, spawning misinformation and spreading doubt about results, particularly in close races.