MILWAUKEE — In a state where Mr. Trump won by less than one percentage point in 2016, any bloc of voters could swing this year’s election, and in Wisconsin, older voters comprise a formidable group.

Not only does Wisconsin have a larger share of older adults than the national average — and in many counties, 30 percent or more of the population is age 60 and over — but the state’s older voters also head to the polls in big numbers.

In the 2018 midterm elections, 76 percent of Wisconsin citizens age 65 and older voted,according to census data — more than in all but six other states. 

In interviews, many older Wisconsinites said they had already safely voted.

“My ballot was mailed to me and my son took me to City Hall to drop it off,” said Grace Clausen, 92, of Greenfield, a Milwaukee suburb. “The slot went right into the building like a mail slot, and it was marked with a great big sign.”

A poll of Wisconsin this month by The New York Times and Siena College showed Mr. Biden with a double-digit advantage among voters over 65, 53 percent to 42 percent.

Both candidates have campaigned in Wisconsin in the race’s final days. And television ads from both parties compete for senior voters in the state, each insisting that its candidate will protect Medicare and Social Security.

But many voters said their life experiences influenced their choices more than political ads. And the interviews suggested that Mr. Trump might be in trouble among this older demographic.

For two retired priests who, like Ms. Clausen, live in a Catholic senior community, Mr. Biden was an easy choice.

“For me, the environment is the biggest issue — if we don’t take care of that, there is no future,” said Father Ed Eschweiler, 99. “Certainly, no right to life is going to be effective if we can’t breathe or drink the water or eat the food from the soil. I don’t think our president has done anything significant on right-to-life, other than the appointment of three Supreme Court judges.” 

Father Tom Suriano, 82, said there were other “pro-life” issues to be concerned about, like “children in cages,” “people dying homeless and hungry on the streets,” and “cutbacks to Obamacare.”

“First of all, Donald Trump is a newcomer to the pro-life camp, but secondly, once the baby is born, he seems to lose interest,” Father Suriano said. “I get angry at people who equate pro-life with being anti-abortion.”

“The president is not very well-liked,” observed Shirley Cohen, 92, a resident of a Jewish senior community in Milwaukee. Gun control is “absolutely” her top issue, she said, citing her disgust over images of “pro-Trump militias” carrying long guns at protests.

Memories of marching for civil rights during the 1960s influenced a vote for Mr. Biden by Cindy Labucki, 76, of Milwaukee. “I certainly condone the peaceful demonstrations for Black Lives Matter,” said Ms. Labucki, a retired teacher.

Marion Jaeger, 96, of Oconomowoc remembers the Great Depression and how grateful her father, an immigrant, was for President Franklin D. Roosevelt’s social programs.

Although she has voted over the years for both parties, Mr. Biden’s “respect” and
“presentation” won her over.

“I don’t know that most people in this building appreciate some of the comments that Republicans have been making, whether their agenda is good or not,” said Ms. Jaeger, who lives in a Lutheran senior complex. “Mr. Trump’s demeanor is not presidential.”

Health care was a top priority for Marylouise Felhofer, 68, a retired Navy nurse, also of Oconomowoc. “The Affordable Care Act could be enhanced, but I don’t think it should be repealed,” she said.

But Ms. Felhofer’s neighbor, Mickey Laughland, 83, cast her vote for Mr. Trump. “He’s not a politician — he doesn’t owe people favors,” Ms. Laughland said. “I wish he’d quit tweeting, but by gum, he’s done what he said he would do.”

Wesley Martin Jr., 77, president of the Great Lakes Native American Elders Association, predicted that most voters in Wisconsin’s Menominee and Oneida reservations would choose Mr. Biden, as he did. He cited environmental protections as a key issue, along with Mr. Trump’s history of clashing with tribal-run casinos. 

In Wisconsin’s far north, tourists and wealthy people with lake homes belie the area’s rate of poverty, said Erv Teichmiller, 82, a Methodist minister and former Vilas County Board supervisor.

“Our area tends to be Republican, probably two to one,” said Mr. Teichmiller, who predicted that Mr. Trump would win in the region, but by a smaller margin than in 2016. “A fair number of people are tired of his bullying and lying and are concerned about Obamacare being taken away.”