SCOTTISH Conservatives are to lead the charge against Boris Johnson’s push for the Tory leadership, warning that if he succeeded, it would be “a nightmare” for Ruth Davidson and could kill off her bid to become First Minister.

The Herald has been told that private polling for the party has shown that a Johnson premiership would be the “only thing” that would seriously damage Ms Davidson’s political fortunes.

One Tory MP at the Conservative conference in Birmingham described the prospect of the party being led by Mr Johnson as “a nightmare scenario for Ruth,” saying: “It would lead her badly exposed. The Nats and Labour in Scotland would have a field day.”

The suggestion is that Ms Davidson, as a leading Remainer, would be constantly at odds with Mr Johnson as he sought to pursue a hard Brexit.

Another insider declared: “We can’t allow a Johnson leadership to happen,” making clear Scottish Conservatives would mount a concerted “Stop Boris” campaign should Theresa May’s premiership be seriously threatened.

A third source claimed grassroot Tories north of the border were taking against Mr Johnson for his “self-serving” actions such as his notorious “suicide vest” comment on the Chequers Plan and his decision to absent himself from the Heathrow vote.

He added: “Scots are fair-minded and they do not like self-serving people. It’s clear Boris is putting himself and his ambitions before the good of the party and the good of the country.”

Mr Johnson, who makes his only scheduled appearance at the conference this lunchtime at a fringe event, dubbed the “chuck Chequers rally,” was yesterday photographed running through what was described as a field of wheat.

It was being interpreted as a deliberate bid to mock the Prime Minister, who was once asked what the naughtiest thing she remembered doing as a child was and replied running through a farmer’s wheat field.

Earlier, Philip Hammond launched a personal attack on the former Foreign Secretary, making clear he believed his Tory colleague would never be Prime Minister.

The Chancellor sought to imitate the Old Etonian’s delivery saying: “Boris sits there and at the end of it he says: 'Yeah but, er, there must be a way, I mean, if you just, if you, erm, come on, we can do it Phil, we can do it. I know we can get there.' And that's it.”

He also rubbished Mr Johnson’s super-Canada trade deal proposal as a “fantasy world” and suggested his former Cabinet colleague was a “big personality,” who could not grasp detail.

Later, emphasising the Tory psychodrama on Brexit, David Davis launched a counter-attack on Mr Hammond, accusing him of trying to “frighten the country to death” over EU withdrawal by using inaccurate Whitehall forecasts, which he said his former Cabinet colleague had used as “weapons”.

The onetime Brexit Secretary told a conference fringe event: "It used to drive me mad sometimes when Government ministers, I'll name no names but you can make a very easy guess - he's been on the air today - we'd get to a negotiation point and suddenly somebody over here would start saying: 'Oh, we are in a terrible problem here, we can't do this, we can't do that, we are in difficulty, all these companies are going to leave the country.' No they are not."

Mr Davies added: "We shouldn't frighten ourselves to death."

Meanwhile in her conference speech, Ms Davidson also took aim at Mr Johnson, denouncing the “ivory-towered schemes of the ideological puritan” and called for Tory pragmatism on Brexit otherwise, she warned, the keys of Downing Street risked being handed to Jeremy Corbyn.

Declaring how she believed in the national interest, the Scottish Conservative leader told conference to applause: “I stand by the Prime Minister.”

Earlier this week, Ms Davidson described as “unwise” the former Foreign Secretary's putdown of Mrs May’s Chequers Plan when he denounced it as “deranged”.

Last month, after Mr Johnson said burkas were “oppressive” and made women look like “bank robbers” or “letter boxes,” the Scottish party leader said Muslim women who wore burkas should be defended in the same way as Christians who wore crucifixes.

Today in Edinburgh, Nicola Sturgeon will seek to pile pressure on Mrs May ahead of her keynote conference address tomorrow.

In a speech, the First Minister is expected to describe the PM’s plan to take Britain out of the single market as an “act of wilful economic vandalism”.

She will call on Mrs May to “face up to reality” and argue that after the fiascos of the last few weeks, with the Chequers Plan being exposed as untenable, staying in the single market post Brexit is now a "stronger political possibility" than it has been for the past two years.

But at conference today, David Mundell, the Scottish Secretary, will accuse the SNP leader of trapping Scotland in a “damaging constitutional Groundhog Day” and repeat his call for Ms Sturgeon to take her plan for a second independence referendum off the table.