People who were on summer vacation on the day of the last presidential debate will not believe their eyes when they watch the next debate.

Tuesday’s debate between Vice President Kamala Harris and former President Donald Trump marks the culmination of 75 days of unprecedented campaign chaos — and the beginning of a 55-day race to Election Day through equally uncharted waters.

“It’s like running a 5K after being in the Tilt-A-Whirl: The world is spinning and you have to quickly figure out what’s up,” said Democratic strategist Jared Leopold.

In the 2½ months since Trump and President Joe Biden faced off in late June, several fundamental aspects of the race have been upended, with one candidate replaced and the other nearly killed.

Follow live updates on the 2024 electionThe parties have made new national figures of a pair of vice presidential candidates: Sen. J.D. Vance, R-Ohio, and Minnesota Gov. Tim Walz. Trump’s criminal trials, which were expected to dominate the campaign’s final stretch, are out of the picture, thanks to a Supreme Court ruling the week of July 4.

The best polls The third candidate of a generation, Robert F. Kennedy Jr., saw his popularity plummet and dropped out of the race, endorsing Trump.

The parties even reversed their position on the rules of debate, with the Harris’ campaign (unsuccessfully) pushed for open mics throughout the debate after Biden’s team has advocated turning off candidates’ microphones when they are not speaking.

Craig Snyder, a Philadelphia political activist and author of a new presidential campaign novel titled “Guile,” said fiction writers can’t get away with something as unexpected as the reality of this year’s election.

“The facts of the 2024 campaign so far would probably not be approved as fiction. It just wouldn’t seem credible that so many unprecedented events could happen in succession,” said Snyder, a Republican who runs Haley Voters for Harris, a group of Nikki Haley supporters who support Harris. “Yet with all these improbable plot twists, here we are on the day of what could be one of the most important political debates in American history — perhaps the second-to-last — and yet it’s a race that’s right back where it started over a year ago — a tie!”

And now, in the home stretch of the campaign, after the conventions and with early voting about to begin in some states, the real campaign between the two candidates who will actually face off in the general election is finally beginning in earnest. The stakes are higher on Tuesday, as the first and possibly only debate between two people who have never met in person takes place.

“What happens on these nights lives on. Just ask Joe Biden,” Republican strategist Matt Gorman said. “Kamala wants to come out of this with a rallying cry. Expect the Harris campaign to inject something into the campaign or start a narrative that they hope to continue for weeks.”

Now Democrats have the younger candidate with the fundraising advantage and big crowds — a complete reversal from a few months ago — while Trump has remained Trump, even as some allies insisted he was a changed man in the days immediately following the attempt on his life in a mid-July meeting in Pennsylvania.

“This debate is essentially a funhouse mirror of the first debate: Trump is the same, but now that Harris is facing him, he looks significantly older, sounds more disjointed and comes across as dramatically more out of touch,” said Democratic strategist Caitlin Legacki.

And, Legacki said, Harris can now talk more effectively about abortion — the top issue for Democrats — than Biden ever could, given his personal discomfort with the issue.

Now that the current president is gone, the former president and current vice president are both pseudo-presidents trying to act as change agents while simultaneously holding back the accomplishments of their time in the White House.

That dynamic has clouded both candidates’ policy agendas, with both candidates failing to provide details on key policies and making contradictory or at least ambiguous statements about longstanding positions.

At times, Trump seems to be reeling from his change of opponent. At first he insisted (hoped?) that Biden would vote again, but now he occasionally makes Freudian slips by calling his opponent Biden.

Meanwhile, Democrats have woken up from their Biden-era posturing, but they’ve had their own growing pains under the new administration.

After living in despair for nearly a month as Biden’s poll numbers plummeted following his disastrous June 27 debate, Biden announced via social media that he would step aside and give Harris his endorsement, plus the $96 million his campaign had in the bank.

The news, posted while Biden was Recovering from Covid-19 at her beach house, Harris brought ecstasy and good vibes in July and August, as she secured the nomination, picked Walz and convened the party at the national convention. But there are signs that momentum was starting to wane heading into the debate, as she faces increasing criticism for avoiding reporters and providing few details about her policy agenda.

Harris’ campaign didn’t post a policy page on her website until Monday. And the platform her party adopted at last month’s convention was written before Biden withdrew, and it wasn’t redacted to avoid reopening messy issues like Israel’s war in Gaza.

And despite the vibes and improved numbers, Harris is telling her supporters she’s still an “underdog” to Trump, using polls usual show results within the margin of error and all signs point to an extremely close election.

“No matter how you look at this race, it’s a toss-up,” pollster Richard Czuba, founder of the Lansing-based Glengariff Group, said of a recent Detroit News-WDIV-TV poll of Michigan voters that echoed what virtually every other pollster has said in virtually every other poll.

Because America survived the past 75 days of chaos, it now gets 55 days of unpredictability, something rarely seen before in modern history.