WESTERVILLE, Ohio — Kate Rabinovitch doesn’t call herself an activist.

A few weeks ago, the 29-year-old real estate agent wrote personalized messages to voters in her home state of Ohio on behalf of Joseph R. Biden Jr. She texts with undecided friends during the debates, arguing for the Democratic nominee. And she is helping to organize voter drives in her suburban Cleveland neighborhood.

But a political activist? No way.

“It’s just not something that I ever would have described myself as, if you talked to me a year ago,” said Ms. Rabinovitch. “I’m just a mom with the feels, like hard feels.”

Four years ago, Ms. Rabinovitch agonized over which candidate to support. In the final minutes of voting, she walked into the booth still uncertain. She left having cast her ballot for Donald J. Trump.

“I thought, ‘Oh, what’s the worst that could happen?’” she recalled recently. “I do feel guilty.”

For much of the country, polarized views about the president and his chaotic upending of American politics haven’t budged since 2016, when he squeezed out a narrow Electoral College victory while losing the popular vote. Yet, there is a demographic group that has changed its mind: white women in the suburbs.

In 2016, the suburbs powered Mr. Trump’s victory, with exit polls showing that he won those areas by four points. Now, polling in swing states shows the president losing those voters by historic margins, fueled by a record-breaking gender gap. Mr. Biden leads by 23 points among suburban women in battleground states, according to recent polling by The New York Times and Siena College. Among men, the race is tied.

Mr. Trump’s suburban deficit has emerged as a significant problem for his re-election bid, one that’s left the president begging with women to come home.

“Suburban women, will you please like me?” the president said at a rally in Johnstown, Pa., this week. “Please. Please.”

For Ms. Rabinovitch, no amount of exaggerated pleading will undo the damage of the past four years. On a chilly October evening in a suburban Columbus backyard, she gathered with three other women, all mothers of young children, to discuss their political evolutions.

Not all of them voted for Mr. Trump, but all carry regret about 2016. For them, the president’s words and actions have forced an intimate re-examination of their deep-rooted, more conservative political identities — taught in church and school and inherited from their families — and some things that are even more personal: their sense of morality and the values they hope to impart to their children.

Perhaps most worrisome for the president and his party is that the shift could go beyond Mr. Trump on the ballot this year, and outlast him. Armed with insulated tumblers of wine, the women described how Mr. Trump had turned them off from a Republican Party they once supported, one that they now see as intertwined with the president’s divisive rhetoric.

“I cannot imagine a Republican candidate that I would rally behind,” said Hannah Dasgupta, who is a stay-at-home mother of two school-age children and grew up in a conservative home. “Wow, that’s mind-blowing to think about. That’s a huge departure.”

Ms. Dasgupta, 37, said she had never liked Mr. Trump but had been unable to support Hillary Clinton in 2016. For Ms. Dasgupta, who was raised attending Christian schools, opposition to abortion was central to her political beliefs. After Mrs. Clinton offered an unapologetic defense of abortion rights in the final presidential debate, Ms. Dasgupta cast her ballot for Gary Johnson, the Libertarian candidate.

“The crazy thing is like, I wouldn’t know the guy if he was sitting next to me,” Ms. Dasgupta said. “I don’t think I could identify him. But those Republican roots were deep, and the abortion issue is strong.”

Over the past four years, Ms. Dasgupta’s views on abortion have shifted to the left as her opinion of the president has sunk. She has grown tired of explaining his actions — such as his comments in this week’s town hall questioning the effectiveness of mask-wearing — to her young children.

She connects her support of Mr. Biden to her role as a mother, saying that she spends time teaching her children basic skills like sharing and speaking respectfully — traits she believes the president lacks.

“In the last four years, my children have grown and developed more than he has in regards to the way he speaks to other people, the way he speaks about other people,” she said.

Katie Paris, the founder of Red, Wine and Blue, an all-female team of “P.T.A. mamas and digital divas” focused on organizing suburban female voters for Ohio Democrats, hears such sentiments frequently.

She believes that for Democrats to keep the support of women like Ms. Dasgupta, they must recognize the intimate nature of their politics. Ms. Paris’s philosophy of political organizing is a mix of David Plouffe, the famed Democratic data guru, and Brené Brown, the research professor who has become a viral self-help star.

Ms. Paris, who brought together the group of women around the backyard firepit, believes that moving away from a political identity takes “courageous conversations.” And the way to encourage people on that path involves “being vulnerable with each other about what’s going on in our lives at a personal level.”

Many suburban women already have doubts about Mr. Trump, she said, but may be reluctant to express their political opinions, particularly to a young campaign organizer from out of state. Her group hires as organizers women who have lived in their suburban communities for over a decade, tapping into their existing networks of class parents, tee-ball coaches and room parents.

“We can’t leave this all on Black voters to carry all the weight in Ohio,” added Ms. Paris, who is white. “It’s going to take all of us.”

She and her team are particularly proud of their large presence on social media. One recent viral effort featured women posting photos of themselves in aprons and curlers with Democratic campaign signs while holding cocktails, a spoof on Mr. Trump’s Twitter appeals to the “Suburban Housewives of America.”

Ms. Paris and the Democrats hope to repeat the strategy that won their party control of the House in 2018, driving up their margins among suburban women in swing districts.

They have some reason for optimism: Four years ago, Mr. Trump won Ohio by eight percentage points. Now, polling shows a tied race. Still, Ohio may remain out of reach for Democrats this year. The 2018 strategy was far less succesful there than elsewhere in the Midwest, and the popular incumbent Senator Sherrod Brown was the only Democrat to win statewide. The perennial swing state has trended Republican recently, and plenty of female voters still support the president.

“I’ve heard people say, ‘How can you vote for Trump when you’re a woman and the things he says about women?’” said Rachel Antonelli, 35, a banker in Delaware, Ohio, who is pregnant with her second child and plans to vote for Mr. Trump. “Personally, what I care about is that he gets things done for the country.”

Since the summer of racial justice protests and unrest around the country, Republicans have tried to woo back white suburban women with a focus on “law and order,” stoking racial fears and depicting the increasingly diverse suburbs as the sole province of white, affluent families. According to William Frey, a demographer at the Brookings Institution, white people made up 77 percent of the population in inner-ring suburbs in 1990; today they are 58 percent, he said.

The women in Columbus, who are all white, described the killing of George Floyd as a seminal event in their political awakenings, one that drew attention to issues of racism and police violence beyond their personal purview.

“I’m not going to lie and say, like, in February, I was worried about racism in America,” said Ms. Rabinovitch, who has a 4-year-old son. “Like, I wasn’t.”

The video of Mr. Floyd’s killing, she said, forced her to acknowledge structural problems in American society.

“I have to think of everybody,” she said. “So if I’m voting against Donald Trump, that’s not a vote for me or a vote for my son. That’s a vote for everyone. Everyone’s sons.”

In the final months of the campaign, the pandemic and its cascading effects on schools and the economy have deepened the opposition to Mr. Trump among female voters.

Unlike some of the women in her social circles, Andrea Granieri knew four years ago that she couldn’t back Mr. Trump. Raised in a conservative Catholic family, her vote for Hillary Clinton was the first she had ever cast for a Democrat.

“I just looked at my daughter, who was 3 at the time, and the way that he talked about and treated women,” said Ms. Granieri, 34, who lives in Anderson Township, a suburb of Cincinnati. “I was just like, I cannot put a check next to his name.”

After Mrs. Clinton lost, Ms. Granieri found herself becoming increasingly engaged in local Democratic causes.Her involvement escalated after the pandemic began, and she found herself juggling a full-time job at a charter school and home-schooling her own children along with the pressure of her husband’s losing some of his work.

“I felt like, do you understand?” she said. “Like, I am on my last shred of sanity here. And you guys have no idea. You’re not sending help. I don’t know how much longer I have to do this.”

A Facebook post she wrote about her frustrations with the state’s Republican leadership captured local attention, becoming a piece of campaign mail for a candidate for the State Senate.

“I had so many regrets after 2016, because I took for granted that — I just thought Hillary would win,” Ms. Granieiri said. “I’m determined not to have regrets on Nov. 4 this time.”

Jessica Cheung contributed reporting.