Who might be Britain's next prime minister if May goes?

Leadsom, another pro-Brexit campaigner who still serves in May's cabinet, made it to the last two in the 2016 contest to replace Cameron. But, rather than force a run-off vote against Theresa May, she withdrew from the contest. She currently runs parliamentary business for the government.

Leadsom said she backed May in the confidence vote. (Reporting by William James, Elizabeth Piper and Kylie MacLellan Editing by Guy Faulconbridge and Peter Graff)