David Cameron has admitted Boris Johnson is aiming to be the next Tory leader . David Cameron has admitted Boris Johnson is locked in a behind-the-scenes battle with Theresa May and George Osborne to take over the Tory leadership . The Prime Minister said the London Mayor had 'suddenly realised ' after years of mischief making that his main political rivals were those lining themselves up to take over the top job . He said Mr Johnson now understood the pair were no longer in 'competition ' . The admission exposes the battle quietly raging behind the scenes over who will take over from Mr Cameron . It comes just weeks after Mr Cameron revealed he would stand down as Prime Minister before 2020 if he wins re-election next month . Mr Cameron said : 'Terms are like shredded wheat : two are wonderful but three might just be too many . ' He named three of his senior colleagues - Home Secretary Theresa May , Chancellor George Osborne and London mayor Boris Johnson - as possible replacements as Conservative leader when he stands down . Speaking to his cousin Harry Mount in an interview with the Sunday Times , Mr Cameron also admits that his membership of the infamous Bullingdon Club at Oxford is 'cripplingly embarrassing ' . Mr Cameron denied that he and the London Mayor have been political rivals for decades . But he admitted that Mr Johnson had , until recently , seen the PM as his competition . He said : 'He suddenly realised I 'm not really his competition . His competition is people who 'll have a crack at it after me . ' Mr Cameron said he saw his relationship with the London Mayor as 'co-opetition ' . He said : ' I wanted him to stand for London mayor . George and I helped persuade him to do that . And he 's done it brilliantly . ' A Conservative is running the most successful city on earth , and is winning elections . ' Mr Cameron said he remembered the London Mayor at Eton 'because he was so striking ' . Boris Johnson has 'suddenly realised ' that David Cameron is not his 'competition ' . The Prime Minister said : 'His competition is people who 'll have a crack at it after me ' Chancellor George Osborne , pictured campaigning in Brentford this morning , and the Home Secretary Theresa May were named by the Prime Minister as potential successors . David Cameron 's 11-year-old daughter regularly teases him for leaving her in the pub , his wife Samantha has revealed . Nancy jokes that she will write a memoir about her life as the daughter of a PM . Mrs Cameron said : 'She 's always , like , ' I 'm on Chapter Five of Daddy , How Your Life As Prime Minister 's Affected Me . Chapter Two is when you left me in the pub ' . ' Mr and Mrs Cameron were left 'distraught ' after leaving the then 8-year-old in the Plough Inn in Buckinghamshire after a Sunday drink in 2008 . The Prime Minister , meanwhile , has told the Sunday Times that the family is kept together by his wife . He said : ' I love her as much today as when I first met her ; more . Much more . ' Mr Cameron added : 'It 's easily the best thing that 's happened in my life . I 'm very blessed to have her . She is amazing . ' He said : 'He was dishevelled . I remember watching him play rugby . He was ferocious . Built like a second row . ' The Prime Minister also revealed that he had lost almost half a stone since Christmas after going on 'just a little bit ' of a diet . Overall he lost 'two kilos ' . Mr Cameron 's admission that the London Mayor is lining up a tilt at the Tory leadership comes after Mr Johnson was accused of 'breath-taking cheek ' after he set out his vision of 'moral purpose ' in business and politics . The London Mayor praised the Coalition for having kept down unemployment and not returning to the dole queues of 1980s Britain . He said the fact that more jobs were being created was 'one of the absolute moral triumphs ' of the government . The comments by Mr Johnson , who is standing to be a Tory MP in a west London constituency , were seen as an attempt to position himself as a future party leader . In 2004 , Mr Johnson admitted a four-year affair with the journalist Petronella Wyatt while he was married to his second wife Marina , with whom he has four children . Five years later he fathered a child by Helen Macintyre , an unpaid adviser in the London Assembly . Mr Johnson spoke about morality in an interview with the London Evening Standard , saying he believed wealth creation was there to fund public services such as schools and hospitals . He said : ' I think this country was harrowed by the experience of mass unemployment in the early Eighties . 'One of the absolute moral triumphs of this Coalition government has been to get us through the worst recession for 50 years without seeing a return to those levels of unemployment . ' But Labour 's Stephen Pound , who is fighting to defend a nearby seat , said : ' I 'm thinking of a sentence with the words pot , kettle and black in it . ' 'It seems that Boris 's motto is 'do as I say , not as I do ' . It really is breath-taking cheek . He obviously has a different definition of 'moral ' to most of my constituents . '
David Cameron revealed that the London Mayor had seen him as a rival . PM said Mr Johnson 'suddenly realised ' his competition was elsewhere . Comes after he named Johnson , Osborne and May as potential successors . Mr Cameron also admitted Eton past 'cripplingly embarrassing '