Vice President Harris is seeing a significant spike in enthusiasm for her candidacy among Democratic base voters — a key metric that is expected to help drive grassroots fundraising, volunteer sign-ups, and the on-the-ground turnout machine needed in swing states. It’s a remarkable change of fortune since Democrats were expressing very little appetite for a second Biden administration. 

According to a new poll released by Monmouth University on Wednesday, Democrats have transformed into one of the most engaged bases in recent political history after earlier being cynical about the 2024 campaign. Today, 85 percent of Democrats say they are enthusiastic about the general election campaign. In June, that number was 46 percent. 

Among independents, enthusiasm has shot up to 53 percent from 34 percent in that same time period. Republican excitement has held steady at 71 percent in the last two months. 

“This is clearly a different ballgame,” the director of Monmouth’s polling institute, Patrick Murray, said. “The nominee change has raised the ceiling for potential Democratic support in the presidential contest by a small but crucial amount, at least for now.”

The level of excitement among Democrats is also notable. In February, as President Biden ramped up his now-canceled re-election bid, 26 percent of Democrats said they were “very enthusiastic” about their party’s nominee. As of Wednesday, 76 percent of Democrats now say the same of Ms. Harris. 

In the survey’s national polling, Ms. Harris leads President Trump, 48 percent to 43 percent. The vice president’s favorability rating is also much higher than Mr. Biden’s. According to the survey, 39 percent of voters have a favorable view of the incumbent president, compared to 47 percent who have a favorable opinion of Ms. Harris. Trump clocks a favorable rating of 42 percent. 

Those numbers helped contribute to a decrease in “double haters,” meaning voters who dislike both the Republican and Democratic presidential nominees. Between Mr. Biden and Trump, 17 percent of voters had a negative view of both candidates. Between Trump and Ms. Harris, 8 percent dislike both nominees. 

“Taking Biden out of the mix and replacing him with Harris has significantly altered a key metric in this race. As we reported last month, Trump–Biden double haters want to shake things up, but they are wary of change that is too authoritarian. Harris appears to provide most of this group with the fresh outlook they desire,” Mr. Murray said. 

The poll was conducted between August 8 and August 12, meaning it began and ended after Ms. Harris had introduced her running mate, Governor Walz. 

Mr. Walz has a significantly higher net favorability rating than his opponent, the Republican nominee for vice president, Senator Vance. The Minnesota governor has a net positive rating of 7 percent, with 37 percent viewing him positively and an unfavorable rating of 30 percent. Mr. Vance has a net favorable rating of negative 5 percent, with 36 percent viewing him positively and 41 percent viewing him negatively.

On questions about who would be a better, more unifying leader for the country, Ms. Harris either leads Trump or ties him. More voters believe Ms. Harris — rather than Trump — understands the issues facing everyday Americans, has the mental toughness to be president, and represents “true American values,” the survey shows.

Trump is also no longer seen as the change agent he once wa, though he still has a small edge over his opponent. Forty-six percent say he would bring about necessary change the country needs, compared to 45 percent who say the same of Ms. Harris. 

The enthusiasm gap and the belief that Ms. Harris can be a change agent just as much as Trump has been a boon for the nascent Harris-Walz campaign. Just since announcing her bid for office in July, her candidacy has raised more than $250 million and has signed up tens of thousands of volunteers. Her rallies this past week with Mr. Walz have all seen at least 10,000 attendees — reminiscent of the first Trump rallies of 2015 and 2016.