Mr. Trump’s appearance in this town of 77,000 on Wednesday night — where he referred to President Barack Obama by his middle name, “Hussein,” and claimed, inaccurately, that the virus was “rounding the corner” — was not intended to win back the suburban women voters who have drifted away from him over the past four years. That is a hill too steep to climb at this point, in this state: Some internal polls show Mr. Trump trailing Mr. Biden by double digits in the suburbs. The rally’s purpose, campaign aides said, was to activate his base. There was the added practical matter of simply securing a friendly venue in the middle of a pandemic that would allow him to hold a mass gathering for more than 20,000 fans.

“They don’t go to Raleigh or Charlotte,” said Morgan Jackson, a Democratic strategist based in North Carolina. “They’re going to Gastonia and Selma and Greenville. They’re playing the outer game to rally his base. They’ve given up on the Mecklenburg County suburban area. I think they’ve given up here on those votes.”

The Trump campaign’s decision to send the candidate to a conservative county he is sure to win may not be a sign of strength. But it is probably his best shot at rallying enough voters to prevail in North Carolina, where Mr. Trump’s most optimistic campaign officials think he will eke out a victory margin of less than 100,000 votes (four years ago, Mr. Trump won the state by about 173,000 votes).