Theresa May is the Tory grassroots favourite for leader to follow David Cameron

Theresa May has moved ahead of Boris Johnson in the future leadership stakes (PA)

Theresa May, the Home Secretary, is the favoured candidate of the Conservative grassroots to succeed David Cameron, according to a new survey.

She has moved narrowly ahead of Boris Johnson, the Mayor of London, in the future Tory leadership stakes. They are both well ahead of George Osborne, the Chancellor, amid growing signs that he could be a candidate when Mr Cameron steps down.

The poll of 1,000 party members by the ConservativeHome website puts Mrs May on 23 per cent, with Mr Johnson on 22 per cent. “This shows the quiet but relentless rise of a minister who members evidently believe to be delivering on cutting crime, reducing non-EU immigration and police reform,” said Paul Goodman, the editor of ConHome.

Michael Gove, the Education Secretary, is backed by 14 per cent of Tory members, the same proportion as William Hague, the Foreign Secretary. David Davis, the former Shadow Home Secretary, is backed by 10 per cent, putting him ahead of Mr Osborne (6 per cent); Philip Hammond, the Defence Secretary (4 per cent), Owen Paterson, the Environment Secretary (3 per cent) and Chris Grayling, the Justice Secretary (2 per cent).

Mr Osborne, who would probably have Mr Gove’s support if he ran for the leadership, has bounced back after recovering from his “omnishambles Budget” of 2012 and is increasingly being talked of as a “stop Boris” candidate. But Mrs May has made clear she is ready to assume that role.