For the Democrats, the party is over. Now comes the hangover.

CHICAGO – So, the party is over.

The Democratic National Convention – a four-day whirlwind of rousing speeches, late-night parties, policy panels and tens of thousands of attendees from across the country feeling rejuvenated by the prospect of victory in November – has come to an end.

Now comes the hard part, when the hangover sets in: Democrats must maintain this overwhelming momentum for 72 more days and mobilize masses of voters to support Kamala Harris’ presidential campaign. If they fail to do so, there is a very real possibility that she could lose to former President Donald Trump, given that the race is currently so close that it could ultimately be decided by a handful of votes in certain swing states.

Former First Lady Michelle Obama summed up this harsh reality Tuesday night in what was by far her most powerful speech of the convention: “Michelle Obama is asking you – no, I am telling you all – to do something.”

HuffPost was certainly a mood killer at the convention, as the newspaper went around asking enthusiastic delegates and attendees if, given the current polls, they could see that Harris could lose.

Rep. Melanie Stansbury (D-N.M.) acknowledged that the ongoing celebrations at the convention may serve to cover up the reality that the race remains extremely close.

“This worries me greatly,” Stansbury said.

She drew some parallels to Hillary Clinton’s 2016 presidential campaign, when Democrats went into the election overconfident of victory, only to see her lose to Trump. Buoyed by mistakenly optimistic poll numbers in key states and an over-reliance on data analytics, the Clinton campaign famously began with television ads in Texas, which was never actually in the race. In contrast, Clinton never made a personal campaign appearance during the general election in Wisconsin, a state where Trump narrowly defeated her.

Even though the political landscape has changed dramatically since then – millions of women demonstrated against Trump, thousands of women ran for political office in 2018, social media has “gone more democratic” and pollsters have updated their methods to reflect changing voting behavior – Stansbury said fears of a repeat still linger because so much is at stake and Democrats have only a few months to educate voters and increase turnout.

“I think we’re all living with the PTSD of 2016,” she said. “Even though we know she’s the most qualified candidate ever, we can’t handle the nightmare that would come our way if we don’t go out and make sure people show up to vote. We can’t lose this election.”

Two participants from Maryland, Kimberly Fernandez and Jarra Childs, summed up how they felt at the end of the conference.

“Motivated. Successful. Hopeful,” they said.

While acknowledging how close the race is, Fernandez, 41, said she is “confident” Harris will win and said she is ready to volunteer at home.

“I have a personal commitment now to keep going. It’s not all on Kamala,” Fernandez said. “What I learned this week is that we all literally do our part and we need to continue to do that. We need to make sure we stay engaged. We’re in this together.”

Childs, 42, admitted she probably won’t volunteer, but she said she was impressed by Harris’ nomination acceptance speech.

“That motivated me to tell other people about her,” Childs said. “Hear what her politics are and encourage them to get involved.”

Neither doubted that Harris can run an energetic and inspiring campaign through November. They pointed out that Harris had just been chosen as the nominee after President Joe Biden dropped his re-election bid last month, and compared her to an Olympic athlete who finishes a relay race, takes the baton and runs the final lap for the team.

“She’s not hungover,” Fernandez said, perking up as she spoke. “She should still be in good spirits. She can get us to the finish line. Everyone else ran a marathon. She’s fresh. She’s stretching. She’s good.”

Although the race remains close, Democrats have reason to feel pretty damn good right now. Pollsters in both parties have watched in awe as Harris’ last-minute entry into the race dramatically increased the Democrats’ chances of winning the White House.

“We went from 1-3 to 50-50,” Jill Normington, a veteran Democratic pollster and partner at Normington Petts & Associates, told HuffPost. “That’s a huge change in such a short period of time.”

While a Wednesday panel Normington, one of the pollsters at the party conference, pointed out that recent polls showed that women and young voters in particular were enthusiastic about Harris.

“We’re seeing a fundamental shift in enthusiasm and voting intent,” she said. “When you put those two things together, you see a radically different campaign today than you did a month ago.”

Abortion rights are also a driving factor in this election cycle, in a way that benefits Harris. Polls show that Americans are overwhelmingly angry about the overturning of Roe v. Wade by a conservative-majority Supreme Court in 2022 and the subsequent restrictions on women’s reproductive rights in several states.

“There’s a maxim in American politics that says angry people vote,” Normington said during her panel. “The Republican Party has never had a presidential election where anger was on our side on this issue.”

But while the Democrats’ new hope and joy are real, that doesn’t mean Harris has the ball rolling.

“Everyone on the campaign trail and every practitioner is still waking up in a sweat,” said Evan Roth Smith, a Democratic pollster at Blueprint, a polling group. “We know it’s a 4- to 6-point race.”

Still, he said it was “extremely important” that Democrats feel genuine enthusiasm about the prospect of Harris becoming president, even if the course of the race were to change again, which is entirely possible.

“You know what? We’re finally at the top. People are excited,” Smith said. “And you know what? Let’s give ourselves a week to pat ourselves on the back or reassure ourselves that it’s worth giving it our all.”

Some party attendees rejected the notion that Democrats, who experienced an emotional rollercoaster of joy and tears throughout the convention, did not fully understand how much work lay ahead of them to help Harris win.

“It’s supposed to be tough. It’s a very divided country,” says Hassan Martini, executive director of No Dem Left Behind, a group that advocates for rural Democrats.

“I would say we are fortunate to be able to say it will be close. A few months ago we were not so optimistic,” Martini said. “I think this is the hardest election of our lives. The last one was the most consequential. This one will be the hardest.”