After presidential debates in Miami, Detroit and Houston, the leading contenders for the Democratic nomination will face off once again on Tuesday night, not in a big city or a sprawling metropolis, but instead in Westerville, Ohio, an affluent suburb north-east of the state capital, Columbus.

Westerville is perhaps best known locally as the place the former Ohio state governor and Republican presidential candidate John Kasich calls home. But it – and suburbs like it – is also, Democrats say, “ground zero” in the battle for the White House in 2020.

“These suburbs, even more than the rural parts of the state, were the pre-Trump base of the Republican party,” said David Pepper, the chairman of the Ohio Democratic party. “If all of a sudden Republicans are not able to run up the numbers in places like Westerville, that is a very real obstacle on their prior path to victory.”

In 2018, Democrats won the House majority in a “suburban revolt” led by women and powered by a disgust of Donald Trump’s race-based attacks, hardline policy agenda and chaotic leadership style. From the heartland of Ronald Reagan conservatism in Orange county, California, to a coastal South Carolina district that had not elected a Democrat to the seat in 40 years, Democrats swept once reliably Republican suburban strongholds.

In Ohio, Democrats lost a fiercely contested governor’s race but made gains in the state house for the first time in nearly a decade, all of which came in suburban districts, including one that covers Westerville.

Democrats see this trend moving more sharply in their direction in 2020, spurred by a confluence of the president’s increasingly erratic behavior as he faces impeachment, growing economic anxiety and rising frustration over inaction on gun control after a string of mass shootings, including in Dayton, Ohio, where a gunman killed nine people in 32 seconds.

There is no way Democrats win without doing really well in suburbs Lanae Erickson

“There is no way Democrats win without doing really well in suburbs,” said Lanae Erickson, a senior vice-president at Third Way, a centrist Democratic thinktank.

She said suburban voters, and particularly well-educated women, are repulsed by Trump’s hardline immigration agenda that separates families and his racist attacks on congresswomen of color. But neither are they looking for “a far-left socialist takeover”, she said, warning that Democrats risk overreaching on policy by embracing a single-payer healthcare system and decriminalizing illegal border crossings.

“Trump is making Democrats’ job easier in the suburbs,” she said. “But what really delivered these pickups in 2018 was a focus on kitchen table issues like healthcare, housing affordability and education.”

Trump and Republicans have made clear their 2020 strategy is to brand the Democratic field as dangerous “socialists” as a way of hurting their advantage with swing voters wary of the president.

While Trump has found success by driving up support in less densely populated and rural areas, some Republicans have questioned the long-term durability of this strategy.

After Democrats won the House in 2018, Eric Cantor, the former Republican House majority leader, called on Republicans to put forward a “suburban agenda”.

“There is no doubt that some of the loss in support this year from college-educated women, for example, is a result of the negative opinion these voters have of President Trump,” he wrote in the New York Times. “But it is also true that Republicans have not had much to offer suburban voters on what they consistently say are their top issues, including health care, child care, education, the environment and transportation.”

In 2018, voters in the Richmond suburbs of the district Cantor once represented elected the moderate Democrat and political newcomer Abigail Spanberger.

•••

The residents of Westerville, as in many of the suburbs where voters are turning against Republicans, are wealthier, whiter and more educated than the state as a whole.

But the suburbs are changing. They are becoming more diverse and more economically and racially stratified. The rate of poverty in the suburbs is now higher than in many urban areas, a majority of adult residents do not have a college degree and more than a third are minorities.

A central feature of the ideological debate shaping the Democratic primary is over which candidate can best reconcile the economic interests of wealthy, white professionals and poorer and nonwhite liberals.

There are short-term political gains for Democrats in winning over suburban voters but that doesn’t necessarily lead to progressive policies Lily Geismer

Lily Geismer, a historian at Claremont McKenna College and the author of Don’t Blame Us: Suburban Liberals and the Transformation of the Democratic Party, argues that there is a “policy cost” to an electoral approach that prioritizes voters in well-educated, white suburban areas, and particularly women.

“There are short-term political gains for Democrats in winning over suburban voters but that doesn’t necessarily lead to progressive policies,” she said. In her research, Geismer found that many suburban Democrats supported a national liberal agenda while opposing measures that challenged economic inequality in their own neighborhoods.

It’s why, she said, two of the most liberal states in the nation – Maryland and Massachusetts – re-elected Republican governors in 2018. Similarly, voters in states such as California and Washington, which have prided themselves on leading the resistance to Trump’s agenda, rejected progressive ballot measures that would have respectively imposed aggressive rent controls and a tax on carbon pollution.

•••

Democrats’ arrival in Ohio has revived a simmering debate over Ohio’s status as the nation’s most reliable bellwether. No president since John F Kennedy has won without winning Ohio. But the state has not kept pace with the demographic changes transforming the country, resulting in an electorate that has grown increasingly older, whiter and less educated than the rest of the nation.

In 2016, Trump won the state by 8.5 percentage points – the widest margin of any swing state even as Hillary Clinton won the national popular vote by 1.2 percentage points.

“Ohio being selected as a debate site is a nice consolation prize. But don’t mistake it as a fundamental shift in the 2020 political map,” Bret Larkin, the former editorial director of the Plain Dealer, wrote in an op-ed. “And Ohioans should not expect to see much of the party’s nominee in the crucial months of next August, September and October.”

But Pepper, the Ohio Democratic party chair, believes a Republican reckoning in the suburbs gives Democrats a “real shot” at winning Ohio in 2020.

Several recent polls have indicated bad news for the president in the state. A recent Emerson poll of Ohio voters found that Trump’s approval rating in Ohio hovered at 43% with a disapproval of 51%, mirroring his national approval rating. Meanwhile, 47% of Ohio voters said they supported impeachment, compared with 43% who said they did not. The survey also found that in a hypothetical general election matchup, Trump would lose the state to the leading Democratic candidates – former vice-president Joe Biden, the Vermont senator Bernie Sanders and the Massachusetts senator Elizabeth Warren.

Kyle Kondik, political analyst at the University of Virginia’s Center for Politics and author of The Bellwether: Why Ohio Picks the President, said the state reflects the political realignment taking place across the country: voters in the parts of the state that are highly educated and increasingly diverse are turning toward Democrats while working-class white voters continue their migration to the Republican party.

But in Ohio – as in the critical battleground states of Wisconsin, Michigan and Pennsylvania – many political observers believe Trump’s fate might still rest in the hands of the white working-class voters who lifted him to the White House in 2016.

“The state is not ‘unwinnable’ for Democrats, but improvement in the suburbs isn’t sufficient to do it,” Kondik wrote in an email. “The Democrats will have to cut into the Republican margins outside big urban [and] suburban areas as well.”