For months, Gretchen Wolfe of Phoenix has agonised over her choices in this year’s presidential election.

Wolfe, 56, was active for years in her local Republican Party. She voted for former President Donald J. Trump twice, holds more conservative views on border security and is wary of Vice-President Kamala Harris’s spending plans.

But this week — appalled by Trump’s record of election denialism, worried about women’s rights and disgusted by displays of racism at his recent Madison Square Garden campaign rally — she cast her ballot for Harris.

“I felt like I was betraying my party, but country has to come first,” said Wolfe, who works in municipal government. “Even if our country is not better off in four years because of her policies, in four years, we’re still going to have a country where I have sovereignty over my body, and my ability to be the same level of citizen as somebody who has a different gender.”

In a divided nation with very few undecided Americans Left, Wolfe is the rarest of rare voters. Democrats are betting that she is not alone.

As Harris faces alarming signs of erosion with several traditionally Democratic groups, her ability to win over a few more Trump-weary moderate or Right-leaning Americans like Wolfe could play a pivotal role in determining the outcome of a razor-tight election.

“What percentage of them are going to revert to party? Probably most,” acknowledged former Representative Jim Greenwood, a leader of a Republicans for Harris effort in Pennsylvania. “But we’re counting on it being the case that enough Republicans, something like 7, 8, 9, per cent, will not vote for Trump, but will vote for Kamala Harris.”

From suburban Philadelphia to upscale Phoenix neighbourhoods, interviews with more than 50 voters in critical battleground areas made clear that these voters indeed exist, and tend to be particularly bothered by far-reaching abortion bans and the January 6 attack on the Capitol.

Harris, fuelled by notable support from women, has a chance to maintain and even expand the advantages Democrats have built in such places in the Trump era.

But whether Democrats can capitalise on that opening is far from assured in the face of deep polarisation, widespread concerns about the cost of living, realities of racism and sexism, and the fact that Harris serves with an unpopular Democratic President.