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.