Senior Conservatives hoping to succeed Liz Truss as prime minister have begun canvassing support among Tory MPs, the BBC reports.
Ms Truss dramatically resigned on Thursday just six weeks into the job, making her premiership the shortest in British history.
The process has now begun to find a new prime minister by next Friday.
Rishi Sunak and Penny Mordaunt are the likely contenders, while sources close to Boris Johnson neither confirm nor deny he will stand again.
Those putting their hat in the ring will need the support of at least 100 Tory MPs, meaning there can only be a maximum of three candidates.
A handful of Mr Johnson’s biggest political supporters are pressing the former prime minister to make a comeback.
Business Secretary Jacob Rees-Mogg has been encouraging MP colleagues to nominate Mr Johnson, Conservative sources have told BBC News.