Alan Duncan, once Boris Johnson’s deputy at the Foreign Office, has launched a character assassination on his former boss ahead of the Conservative Party conference, which kicks off in Birmingham this weekend.

In the wake of the former foreign secretary's comparison of Theresa May's Chequers plan to a suicide vest earlier this month, Duncan said he would “make sure” of his “political end”. He goes some way towards achieving that objective in interviews with the Times and Spectator, in which he variously describes Johnson as “reckless”, “not a team player, not intellectually focused” and someone who “thinks he can be Britain’s Trump”.

He argued that Johnson has squandered his electoral appeal and essentially needed to be babysat at the Foreign Office, claimed his premiership would be “a course of events which could destroy our prospects for many, many, many years and not be in the national interest”, and said: “He doesn’t know if he’s a journalist or a politician — but he does know it’s all about him.”

Most pertinently, ahead of a conference that MPs anticipate to take the form of an extended beauty contest ahead of May’s expected departure, Duncan claimed that Johnson’s support among the Tory grassroots is a “fiction of journalistic imagination” and suggested he could not win a leadership election. On this, he is probably right – it is difficult to foresee Johnson mustering anything close to the 106 MPs he will need to guarantee a spot in the final round of a leadership contest.

It is brutal stuff, and it is outriding licensed by Downing Street. Johnson’s own pre-conference spin machine whirred into gear today, with several broadcast interviews and a front-page call for a ‘SuperCanada’ Brexit in (where else?) the Daily Telegraph. (Incidentally, the European Research Group's conference fringe event uses the same description for Jacob Rees-Mogg's preferred exit deal.)

In response, Brexit minister Chris Heaton-Harris was dispatched to dismiss Johnson’s plan. “No deal is available without a guarantee that there would be no hard border in Northern Ireland in any eventuality, the so-called Irish backstop,” he said. A “government source” has also briefed journalists that a Canda-style free trade agreement of the sort advocated by the former foreign secretary would “simply guarantee no deal... this is just another very lengthy article which doesn’t offer any answers”.

Ahead of a conference that will be dominated by Brexit and Johnson’s machinations, it is a bold statement of intent from Theresa May. Despite ongoing opposition to her Brexit plans – and repeated threats to her leadership from Johnson and the ERG – she is going for broke. The government machine is taking the fight to the Brexiteers. With the battle lines drawn for conference, there is plenty more to come from both sides.