Andy Coulson, David Cameron's former director of communications, has told the prime minister he can win the 2015 general election if he can expose divisions in the Labour camp and keep Boris Johnson, the London mayor, under control.
In Coulson's view, Johnson is hoping that Cameron fails at the next election so he can ride to his party's rescue – and Cameron is fully aware of the plot.
The advice comes in a 10-point battle plan for victory drawn up by Coulson, which is to be published in GQ magazine this week.
It is the first time Coulson has aired his views on contemporary politics since he was charged in July with conspiracy to intercept phone calls unlawfully while editor of News of the World. He has denied the charges, including allegedly intercepting the voicemail of the murdered schoolgirl Milly Dowler.
His decision to outline his plan for saving Cameron may reflect his frustration at the performance of the No 10 machine, and its failure to protect itself from Ukip, while maintaining a distinctive modernising message.
Coulson suggests No 10 needs a strategy to handle Johnson. He writes: "No 10's Boris strategy should be simple. Support his good ideas, advise privately on the bad ones, but only engage publicly if absolutely necessary – and celebrate Boris's considerable successes."
He reveals that Cameron knows Johnson is after his job. He recounts a discussion with the prime minister in 2008, when Johnson was considering standing as mayor. "Boris Johnson desperately wants to be prime minister and David has known that fact longer than most," he writes.
"When Boris asked me to pass on the message that he was keen to stand as mayor of London, David responded: 'Well, if he wins, he'll want my job next.' …
"If proof were needed that our PM is a man untroubled by self doubt, it came in his next sentence: 'So I think he'll be a bloody brilliant candidate for us' …
"Stabbing David, or anyone else for that matter, in the back would be distinctly off brand – just not very Boris. He would much prefer to see David fail miserably in the election and ride in on his bike to save party and country."
Coulson suggests the Conservatives need to push the Labour leader harder so his policy positions are clarified. He writes: "The prime minister must push him to take positions: expose his strategy (to keep his head down, silently hope that the economy continues to go wonky and, well, just be the other guy), challenge him to take a view on the tricky issues opposition politicians love to duck."
He senses that Ed Miliband's relationship with his shadow cabinet is poor: "I'm struck by how detached the opposition frontbench appears to be from their leader … I just don't think they rate him very much. And if they don't there's a good chance the public will feel the same way once they get to know him properly."
Coulson is predictably scathing about the shadow chancellor, Ed Balls: "The prime minister should pray Ed Balls remains shadow chancellor until the election … Appointing him as George's opposite number was the Miliband gift that will keep on giving … The Tories must look for the divisions and make the most of them a) because they are most certainly real – always a plus – and b) because it's history repeating itself.
"We are in this hole at least in part because of the shamefully dysfunctional Blair/Brown relationship. Labour's two Eds dislike each other and each thinks he is smarter than the other. The Conservatives should imagine in some detail how it would work if they actually won … and share that vision with the British public."
Coulson's plan considers the role of live televised debates in election campaigns. He was a firm advocate of the debates, now seen to have been a mistake due to the sudden increase in Nick Clegg's popularity.
He discusses the rise of Ukip and the extent to which this is due to anti-Europeanism, or fear of immigration. The role of Samantha Cameron, the cabinet secretary, Sir Jeremy Heywood, and the popularity of the foreign secretary, William Hague, is also mulled over.
Many Tory MPs believe Coulson, with his working-class background, might have prevented Cameron being seen as out of touch or part of a public school "chumocracy".
It has also been claimed he would not have allowed Cameron's relationship with the rightwing media to decline, though others blame the phone hacking by newspapers, such as the News of the World, that forced the prime minister to set up the Leveson inquiry and, in turn, propose a royal charter to introduce stronger self-regulation of the press. That, it is claimed, lies at the root of some of the media hostility towards Cameron.
A new poll claimed most voters think the Tories are more divided now than under John Major in the 1990s. Asked whether Cameron is presiding over a more divided party than his Tory predecessor, 56% agreed and 23% disagreed, according to a poll by ComRes for The Independent. Just 29% of those questioned thought Cameron has the leadership qualities to win outright in 2015.
