Keir Starmer's former pollster, Deborah Mattinson, is to meet Kamala Harris's campaign team in Washington this week to share details of how Labour pulled off its stunning election win by targeting key groups of "squeezed working-class voters who wanted change".
The visit comes ahead of a separate trip by Starmer to Washington on Friday to meet US president Joe Biden, his second since becoming prime minister. It will also be his first since Biden stepped down and Harris became the Democratic nominee.
With the race for the White House on a knife-edge, Mattinson, who stepped down from Starmer's office after the election, and the prime minister's former director of policy, Claire Ainsley, who will also attend the briefings, believe the same strategy that delivered for Labour could play an important role in Harris defeating Donald Trump on 5 November.
Writing in the Observer, Mattinson and Ainsley say many of the concerns of crucial undecided voters will be similar on both of sides of the Atlantic.
"These voters - often past Labour voters - had rejected the party because they believed that it had rejected them. Often Tory voters in 2019, they made up nearly 20% of the electorate. Labour's focus on economic concerns, from affordable housing to job security, won them back.
"For Harris, addressing core issues such as housing, prices and job creation could also win over undecided US middle-class voters, many of whom face similar economic pressures. Labour set about finding out as much as possible about these voters and applying that knowledge to all aspects of campaigning.
"They were patriotic, they were family oriented, they were struggling with the cost of living: squeezed working-class voters who wanted change."
Mattinson coined the phrase "hero voters" to describe a group who were more often than not pro-Brexit and persuadable by political leaders if they felt they would address their fundamental core concerns.
The collaboration, they believe, could help tilt the balance by delivering voters in key US battlegrounds.
"Before November's presidential election, Harris has turned on its head a contest that looked like a foregone conclusion in Trump's favour. However, as the data shows clearly, it is still too close to call. We believe that adopting a similar hero-voter approach could make a vital difference, just as it did here in the UK.
"The start point is to identify and understand Harris's hero voters - undecided voters who have considered Trump and live in the handful of the most crucial battleground states."
Mattinson and Ainsley were invited by the Democratic thinktank the Progressive Policy Institute (PPI), with which Ainsley has been working since leaving Starmer's team in late 2022.
Recently, they have been polling among US voters and conducting focus groups to try to understand what will win them over and which groups matter most.
"The context is very different but the parallels are almost uncanny," they write. "This group - who in the US self-define as middle class rather than working class, as the same group might in the UK - is struggling.
"Its members believe that the middle class is in jeopardy, out of reach for people like them, denied the dream of homeownership that previous generations took for granted, unable to cover the essentials, and hyper-aware of the cost of groceries, utilities and other bills. Many work multiple jobs just to keep afloat."
Among those that the two former Starmer aides are likely to meet are Megan Jones, the senior political adviser to vice-president Harris, and Will Marshall, founder of the PPI, who had dealings with top New Labour figures, including Tony Blair, when the party was trying to learn from the electoral success of Bill Clinton's Democrats in the early to mid-1990s, before the 1997 general election.
Mattinson and Ainsley say they had far more time to plan their strategy in detail than have members of the Harris campaign. But they suggest that fine-tuning the Democratic strategy could help sustain recent momentum and give the party a better chance of crossing the finishing line victorious.
"From the point where we defined our hero-voter focus, we had three years to mainline the thinking through party activity. Team Harris has less than three months. But looking at what they have achieved in the past few weeks, success now looks within reach. Hero voters may just help to close that gap."
