Reform UK now has more members than the Conservatives, according to the party’s own tally.
Reform’s online membership tracker put the number at 131,712 at around 11.30am on Thursday, surpassing the last known Tory total of 131,680.
The news will come as a blow to Kemi Badenoch, who has been battling to rebuild faith in the Conservatives after their historic defeat in the general election.
Reform membership has surged thanks to an influx of younger members attracted by a cheaper fee of £10 for those aged 25 and under.
At the weekend, Nigel Farage, the Reform leader, announced that 1,000 young people had joined the party in less than 48 hours.
The Conservatives do not regularly publish their membership numbers. The latest figure was released in November when activists elected Mrs Badenoch as leader.
Meanwhile, Labour Party membership has dropped to its lowest level in a decade. The party lost 37,000 members last year, bringing its total membership at the end of 2023 to 370,450, according to Labour’s official accounts.
The figure marked a new low for Labour membership under Sir Keir Starmer, compared to 532,000 members recorded in 2019 when Jeremy Corbyn was leader.