They have all calculated there is no point challenging now. Why be responsible for the by-election defeat and the disastrous local election results? But they know Starmer is mortally wounded and now politically isolated without McSweeney and Allen.
I expect those who want to take over are also mindful of the adage of whoever wields the dagger never gets to wear the crown.
They also know there is still plenty more material from the Epstein files to be revealed.