(CNN) Amber Pflughoeft beamed with pride as she filled out her ballot for the first time last month.
A 20-year-old who'd been fighting bone cancer for a decade, she was fascinated with politics, her mother Tiffany Pflughoeft remembered. And after spending the last midterm election in the hospital following a bone marrow transplant, she was determined to vote this year.
But just a few days after she mailed in her ballot, Amber's condition took a sudden turn for the worse. She went back to the hospital and died in late September.
Now, her ballot will be thrown out under Wisconsin election law. She is one of several dozen Wisconsinites whose votes will be canceled because they passed away after voting early, according to state Elections Commission data provided to CNN through a public records request.
"She was so excited about it," Tiffany said this week. "She died on a Monday, but on Saturday, when she could still talk, she was telling all the nurses and doctors, 'I voted.'"
"We never realized it wouldn't count," she said.
States around the country are divided on whether to count votes from people who cast an early ballot and then die before Election Day. At least a dozen states allow it, more than a dozen others reject those votes, and laws in other states are unclear, recent research from the National Conference of State Legislatures found.
Among the most crucial swing states, Wisconsin, Iowa, Michigan, North Carolina and Pennsylvania don't count early ballots cast by voters who die before Election Day, while Arizona, Florida, Georgia and Ohio do, according to the NCSL and state elections officials.
This year, when record numbers of Americans are casting ballots early and coronavirus cases and deaths are spiking in some states, it's not just a speculative question. The rules mean that even as Covid-19 has become the defining issue of the presidential race, voters who die in the pandemic won't have their votes count in some states.
Marvin Thielman, an 84-year-old retiree in Chilton, a town of about 4,000 people between Milwaukee and Green Bay, died of coronavirus this month after sending in his ballot by mail, according to state records and his family. Thielman was a strong supporter of President Donald Trump and made sure to fill out his ballot before he went to the hospital, his wife Mildred Thielman said.
"I can't understand why it wouldn't count," Mildred said. "It was important to him."
During the pandemic, the couple -- high school sweethearts who had been together 62 years -- had been careful about wearing masks and staying home as much as possible, Mildred said. But one morning last month, Marvin, who had a history of heart problems and diabetes, woke up yelling that he couldn't breathe. Mildred took him to a hospital, where he was diagnosed with Covid-19 and stayed for the next three weeks. While they called and talked every day, she wasn't able to see him in person again until the day before he died.
A former supervisor at Land O'Lakes, Marvin loved taking road trips, and the couple visited every state except Alaska, Mildred said. He read his local newspaper front to back every day, and especially enjoyed the sports section.
Despite his illness, Marvin didn't blame Trump for his handling of the pandemic, and would have wanted his vote for the President to count, Mildred said.
"He believed Trump did what he could do, because it's a worldwide problem," she said. "Nobody can change what happened."
As Trump and his allies have worked to spread fears about voter fraud, they've often raised the specter of nefarious actors using dead voters' registration to cast ballots.
There have been isolated incidents of attempted fraud tied to dead voters. On Friday, elections officials in Broward County, Florida, said they had received about 50 fraudulent voter registration applications, most of which listed names of people who were verified as deceased, and all postmarked from Columbia, South Carolina, with no return address.
"Somebody went to great pains to exploit the system and it was caught," Broward County elections spokesperson Steven Vancore said. "There appears to be no attempt that this person voted."
Overall, voter fraud is exceedingly rare, according to experts who study it. A sweeping 2007 review by the Brennan Center for Justice found fraud incident rates of between 0.0003% and 0.0025%, and other studies have come to similar conclusions.
"Every study that's attempted to come up with some measure for how often this happens has concluded it is extraordinarily rare for people to attempt to commit voter fraud," said Sean Morales-Doyle, deputy director of the voting rights and elections program at the Brennan Center. "But rhetoric about fraud is generally used to justify anti-voter policies," such as restrictive photo ID laws, increased purges of voter rolls, or restrictions on mail voting, he argued.
Many of the states that deny ballots cast by voters who die before Election Day regularly check death records to update their voter files and remove deceased voters. Still, ballots in those states could be mistakenly counted if election officials don't realize a voter has died before Election Day. And once a ballot is processed and removed from an absentee voter's envelope, it would likely become extremely difficult to track.
Wendy Underhill, the director of elections and redistricting at the National Conference of State Legislatures who has studied the laws, said that states that accepted and rejected votes from voters who died both had fair reasonings.
"One view is Election Day is Election Day, and if you aren't with us on Election Day, your vote doesn't count. The other is that if you're in the early voting window, then your vote does count," she said. "States are going in both directions on that."
Reid Magney, a spokesperson for the Wisconsin Elections Commission, said that there was no ambiguity about the question in state law.
"While our hearts go out to people who have lost loved ones, Wisconsin law is clear that an absentee ballot cannot be counted if the voter has died before Election Day," Magney said. "The law has not changed."
For most family members CNN talked to, the idea that their loved one's ballot wouldn't count came as a total surprise. Marion Roos-Weis, 86, a resident of North Fond Du Lac, Wisconsin, who died earlier this month, made a point of voting in every election, her daughter said.
"I'm sure she would be very, very frustrated to know her vote is not going to count now," said her daughter Linda Roos-Stutz. "It might have motivated her to hang in there a little longer if she had known."
Roos-Weis, who worked for years as a cafeteria worker and bookkeeper in the local school system and loved to bake and garden, typically voted Republican. But she was unhappy with the "disrespectful" way Trump talked about people, and was "very outspoken about racism and injustice," her daughter said.
After leaving her absentee ballot on the table for weeks, she finally filled it out earlier this month, according to her daughter. She didn't let her daughter see who she voted for, but the way she talked about her decision made Roos-Stutz believe she voted for former Vice President Joe Biden, she said.
"Frequently she'd say, 'I want my old country back, I want my old world back,'" Roos-Stutz said.
Florence Sobralske, who died in early October at the age of 95, had volunteered as a poll worker in her central Wisconsin community of Berlin or the nearby town Aurora for many years, her daughter Mary Sobralske said.
"I don't know if they had voter ID in those days, but she wouldn't have had to check it -- she knew everybody," Mary said.
Florence, who raised six kids and once worked as a fur finisher, paid close attention to politics, talking admiringly of Vermont Sen. Bernie Sanders during the senator's presidential bid earlier this year and denouncing Trump, Mary said. Her ballot arrived at her local elections office a few days before she died, according to the state records.
"She would have been very unhappy about it" if she knew her vote wouldn't count, Mary said.
Many of the voters who passed away in Wisconsin had been voting in every election for decades, their family members said. But Amber Pflughoeft, the 20-year-old cancer victim and a resident of the Milwaukee suburb West Bend, was an exception.
In preparation for her first presidential vote, Amber spent time studying Trump and Biden's websites, and would debate politics with friends on Discord, a chat app.
She even had some experience participating in governing herself, going to Washington, DC, as part of a trip organized by a camp for kids who've been diagnosed with cancer, lobbying officials for more funding for childhood cancer rsesearch, her mother said.
While Amber shared a lot with her mom, there was one thing she didn't tell her: who she voted for.
"She liked that the voting process was a secret, that it was something you had for yourself," Tiffany said. "She wanted to make some kind of a difference with her vote, and it's sad that she didn't get to."