Interviews with voters here showed broad frustration with the telegenic Mr. Cawthorn, with many saying he has focused more on being on camera than on his district’s needs. Last year, he set plans to run in a neighboring district that would put him in the Charlotte media market and elevate his profile, but he changed his mind when district lines were officially redrawn. By then, other Republicans had jumped into the race for his seat.

“He’s done nothing for the people of North Carolina,” said Bonnie Whitener, sitting near a giant taxidermied bear that was holding a “Don’t Tread on Me” flag. Two years ago, she had a billboard for Mr. Cawthorn outside her restaurant on a busy highway in Madison County, and she held a fundraiser for him. But now she wants him out of office…

In the GOP primary, which is also open to unaffiliated voters, a candidate must reach 30% plus one vote to win outright. Challengers in the crowded race are hoping to prevent Mr. Cawthorn from reaching that threshold to force a runoff. A polling memo prepared for the Edwards campaign and reported in local media showed Mr. Cawthorn with a lead but said it was shrinking.