Kamala Harris’s campaign has been trying to get voters to feel the joy. Speakers at the Democratic National Convention used the word “joy” dozens of times, including when Bill Clinton hailed Ms. Harris as “the president of joy.”

But how do voters really feel? Does the data back up the vibes?

Polls have registered a jolt of newfound happiness about the election. In July, in the week after President Biden’s decision to forgo the nomination, a New York Times/Siena College survey found that anger and resignation had been subsiding among voters of both parties, while joy had jumped.

Since then, that happiness has apparently deepened, among Democrats in particular. Times/Siena swing state polls in August found that nearly 80 percent of Democrats said they were satisfied with their choice of candidates, a stark shift from May, when just 55 percent said they were.

But the post-dropout Times/Siena national poll also found that voters’ primary emotion surrounding the election was anxiety, which was reported by nearly half of Democrats.

There are many reasons anxiety might persist. Though Ms. Harris’s poll numbers are better than Mr. Biden’s, the race still sits on a knife’s edge. Whether her upswing can continue beyond the probable post-convention bump is still to be seen.

Examining the words voters most frequently used to describe their emotions about the election provides us with a window into just how much the mood has swung, and how it could continue to shift.

Words Democrats most frequently used to describe their feelings about the election

Certain corners of social media are now awash in coconut tree emojis and shaded green squares declaring this Ms. Harris’s “Brat summer.” Democrats’ joy doubled between February and July, with 20 percent of the party’s voters using words indicating happiness, hope or excitement to describe their feelings about the election after Mr. Biden had dropped out, while Democratic despair more than halved.

Ms. Harris has referred to herself and her running mate, Gov. Tim Walz of Minnesota, as “joyful warriors,” and Mr. Walz, in his first speech as the vice-presidential pick, thanked her for “bringing back the joy.”

“The vibe is very high, no doubt about it,” said Nancy Rohr, 68, a retired piano teacher from Orange County, Calif., who used the word “excited” to describe her feelings about November. “I would say it’s her energy; she’s a joyful, energetic person.”

“It just feels really exciting to turn the corner,” she added.

In February, Democrats’ feelings had been dominated by fear and sadness.

Over this whirlwind summer, they have grappled with the duality of joy and fear. The July poll was taken the week after Mr. Biden dropped out of the race; though support quickly coalesced around Ms. Harris, she had not yet officially clinched the nomination. Not only did Democrats use more words indicating joy and hope about the election, they also used words indicating feelings of anxiety and apprehension.

Over the past few weeks, the Harris campaign has tried to put those fears to rest.

Still, anxiety persists. “I’m just more concerned that if one party loses, we’re not even going to have a peaceful transition of power,” said Jeff Fitzsimmons, 42, a manager of a livestock operation from Norman County, Minn., who described his election-related feelings as “nervous.”

Words Republicans most frequently used to describe their feelings about the election

Democrats hardly have a monopoly on joy, even as former President Donald J. Trump has adopted a darker tone during recent weeks, warning of “bad things” to come if Ms. Harris wins.

From February to July, feelings of anger and confusion subsided among Republicans. By summer, nearly three in 10 Republican voters used words indicating happiness, hope or excitement to describe their feelings about the election, rivaling the share who expressed fear or apprehension, which had remained virtually unchanged since February.

The Grand Old Party partied with its own set of stars this summer. “Let’s make America rock again,” Mr. Trump said in a video shown at a summer music festival headlined by Kid Rock.

“I’m excited to have a change,” said Stephanie Rhodes, 61, a Trump supporter from Silverhill, Ala., who runs a small cafe, who used the word “excited” to express her feelings about November. “I’m a small business owner, and the Biden administration has really hurt my business.”

The poll was conducted soon after the attempted Trump assassination and the Republican National Convention, accounting perhaps for some of the increased exuberance among Republicans. Trump supporters saw their candidate emerge from the attempt on his life with a raised fist, a mark of defiance reminiscent of heroes in ancient art.

Still, more than 25 percent of Republicans in July used words like “scared” or “nervous” to describe their feelings about the election.

Joel Daria, 43, an insurance agent from Dublin, Ohio, used the word “nervous,” saying he worried about the future for his daughters under a Harris administration.

“I don’t want them to think that if they get married, they’re a weak woman,” said Mr. Daria. “I don’t want them to be in a world where they can’t own guns if they want to. I don’t want them to be in a world where they have to go to the bathroom with other people that identify as women.”

In the frantic months between now and November, it’s quite likely that voters’ emotions will continue to fluctuate, particularly as the contest gears up after Labor Day.

“There is such a heightened level of attention to this race — it really raises the stakes,” said Carroll Doherty, director of political research at Pew Research Center. “Any slip-ups or hiccups are more magnified and can lead to bigger magnitude changes in public mood.”