Labour’s dire polling record, along with the disastrous run-up to the Budget, has sparked speculation of a challenge to Sir Keir’s leadership.
Possible candidates include Wes Streeting, the Health Secretary, former deputy prime minister Angela Rayner, and Andy Burnham, the Mayor of Greater Manchester.
Other would-be rivals could include Shabana Mahmood, the Home Secretary, and Ed Miliband, the Energy Secretary.
Last month, Downing Street figures let it be known that Sir Keir would fight any challenge to his leadership rather than going quietly – an intervention which only succeeded in heightening speculation.
Meanwhile, Reform’s membership overtook the Tory Party’s on Boxing Day last year, with the latest figures showing it has 123,000 members.
That development has been accompanied by a string of defections, including former Tory chairman Sir Jake Berry, former Cabinet minister Nadine Dorries and Danny Kruger, the MP for East Wiltshire.
Former Tory MP Ben Bradley this week became the latest to join Reform.
Elsewhere, the Green Party has increased its membership from 126,000 to 180,000 since October. Latest figures show the Liberal Democrats are on 83,174 members, a slight fall on the year before. Mr Corbyn’s new party, Your Party, has 50,000 members.
