Fewer than 12,000 votes in Georgia were the difference between Joseph R. Biden Jr.’s 2020 victory in the state and Donald J. Trump’s defeat. Apart from Arizona, there was no thinner margin in the nation.

Four years later, Democrats and Republicans alike are bracing for another squeaker.

“It feels tighter now to me,” said Nathan Deal, a Republican who served two terms as the governor of Georgia.

“It’s going to be close,” Sabrena Brown, a 55-year-old travel agent, said last weekend at a rally in Atlanta where Vice President Kamala Harris starred.

“Just about a point or two,” Brandy Fears, a 37-year-old Trump voter, said outside of a town-hall meeting that the former president headlined in Zebulon, Ga., on Wednesday. “I don’t know what the American people are going to do.”

The final days of the presidential campaign in Georgia — a state vital to Mr. Trump’s path back to the White House and where Ms. Harris is looking to build on Democrats’ recent gains — have been marked by a flurry of activity underlining both parties’ recognition that, once again, the state is anyone’s to win.

With 16 electoral votes, three fewer than Pennsylvania, it’s not the biggest prize. But the razor-thin margins, tantalizing demographics and a feast-or-famine record for both parties have led to a late onslaught that has startled even people who were expecting a frantic finish.