A poll in Iowa that has unexpectedly put Kamala Harris ahead of Donald Trump in what was previously expected to be a safe state for the Republicans has sent shockwaves through America’s poll-watchers.

The Selzer poll carried out for the Des Moines Register newspaper showed Harris ahead of her Republican rival by three points.

Midwestern Iowa is not one of the seven battleground states of the 2024 election, which have consisted of the Rust belt states of Michigan, Wisconsin and Pennsylvania and the Sun belt states of Georgia, North Carolina, Nevada and Arizona.

While political experts and pollsters are very wary of putting too much store in any one single poll, Selzer is a widely respected polling organisation with a good record in Iowa. If Harris were even competitive in Iowa – which Trump won in both 2016 and 2020 – it could radically reshape the race.

The Selzer poll has Harris over Trump 47% to 44% among likely voters. A September poll showed Trump with a four-point lead over Harris and a June survey showed him with an 18-point lead over then-candidate Joe Biden.

“It’s hard for anybody to say they saw this coming,” pollster J Ann Selzer, president of Selzer & Co, told the Register. “She has clearly leaped into a leading position.”

The poll showed that women are driving the late shift toward Harris in the state. If true and borne out more widely, that would also be significant as the Harris campaign has focused on turning out women amid a broad gender gap with Republican-trending male voters. Harris and her campaign have focused on the overturning of federal abortion rights by the conservative-dominated US supreme court.

The reaction among pundits and pollsters was largely one of shock and surprise, though it was also pointed out that a rival polling group still had Trump leading in Iowa.

“This is a stunning poll. But Ann Seltzer [sic] has as stellar a record as any pollster of forecasting election outcomes in her state. Women are powering this surge. Portents for the country?” said David Axelrod, a former top aide to Barack Obama.

“I mean, margins of error exist and polls can be outliers and I doubt Harris will win Iowa, but Selzer is extremely well-regarded and a within-the-margin race in Iowa is not impossible particularly if the reported late shifts to Harris were real,” said Washington Post columnist Philip Bump.

Selzer is the highest-rated pollster on the national US survey done by polling guru Nate Silver, one of the most closely watched polling experts in the US.

“In the world where Harris wins Iowa, she is probably also cleaning up elsewhere in the midwest, particularly in Michigan and Wisconsin, in which case she’s already almost certain to win the electoral college,” Silver said on his website.

However, he also cautioned that another survey had been published on Saturday in Iowa that still had Trump ahead. The Emerson poll put the former US president up by nine points in the state compared with Harris.

“It is incredibly gutsy to release this poll. It won’t put Harris ahead in our forecast because there was also another Iowa poll out today that was good for Trump. But wouldn’t want to play poker against Ann Selzer,” Silver said.

That seemed to prevent any premature celebrations on behalf of many Democrats.

“Celebrate the Selzer poll for 90 seconds and get back to work. We have an election to win,” said Christopher Hale, a former Democrat congressional candidate in Tennessee.