In the historic downtown of Big Rapids, Michigan, The Old Pioneer Store and Emporium and Kilwin’s Chocolate Shop are full of sweet surprises. In 2016, owner Carlleen Rose said she was Trump all the way.

“I was excited to vote for Trump in the very beginning,” she said. “My husband and I both voted for him. I had great expectations. I thought it was really wonderful.”

But she says she became disappointed in Trump’s character. So in 2020, “I kind of plugged my nose and voted for Biden the second time.”

Rose is a quintessential swing voter in a swing state. Swing states are ones that sway back and forth between supporting Democrats and Republicans. Analysts consider this year’s most likely swing states to include Arizona, Georgia, Pennsylvania, Wisconsin and Michigan.

“We had both Republican statewide electeds, as well as Democratic statewide electeds,” said David Takitaki, a political scientist at Michigan’s Ferris State University. “In recent years, we’ve seen it flip back and forth, both in terms of our state House and Senate, and in terms of our statewide electeds, and differences in the 2016 and 2020 presidential campaigns. So Michigan is a purple state.”

The state recently has seen an “upheaval” in polling, favoring Harris, he said.

“If you’d asked me a few weeks ago, I would’ve said, ‘It looks like Donald Trump is on a flight path to winning Michigan.’ Most of the polls showed him ahead. I’ve seen a very significant shift that’s not only played out in enthusiasm but in the polls. Today, I’d have to say it looks like Harris is going to take Michigan.”

But Michigan Republican Party Chair Pete Hoekstra is optimistic.

“We did it in 2016. We think we can do it again in 2024,” he said. “Clearly, it’s ground zero. We win Michigan, we win the presidency.”

Advocates in both parties will be working to track every vote, with Republicans pushing people hard, for the first time, to vote early.

“Obviously, how that benefits us is — we can track who’s voted,” Hoekstra said. “So as we get closer and closer to election day, the people that we need to focus on starts to shrink, or we can just expand our universe to low-propensity voters and those types of things.”

The swing state dynamic means the whole presidential election can come down to people in just a few counties in a few key states. With every vote important, Republicans say a big focus is on election integrity.

Several voters who tried to vote twice in the recent primary in a Michigan swing county were not charged with what would have been alleged felonies, because prosecutors say the voters meant no harm and the double ballots were caught.

“There’s a tremendous amount of pressure in this cycle to make sure that we’ve got election integrity, a lot of concerns about what happens in the city of Detroit, what happens in Wayne County,” Hoekstra said. “And we still have 53 counties — and you’ve got to think about this — we have 53 counties out of 83 in Michigan that have more registered voters than eligible voters… That’s not possible, right? But it is in Michigan. So we’re working very, very closely with the national committee to go in and get as much of that corrected and the voter files cleaned up before the election.”

So, what about our swing voter — candy shop owner Carlleen Rose — who voted once for Trump and once for Biden?

“I am absolutely going to vote for Harris,” she said. “I could not support Biden. He was not capable of being a leader. And so when he stepped down and Harris stepped up, I feel really enthused. I’m excited.”

Proof that in swing states, elections are like a box of chocolates. You never know what you’re going to get.

“Full Measure with Sharyl Attkisson” airs at 10 a.m. Sunday, WJLA (Channel 7) and WBFF (Channel 45).