DOUGLAS Ross can survive Boris Johnson because he's already faced down Scott Brown, the Scottish Tory chief whip says.

Stephen Kerr MSP said described Ross's position as Scottish Conservative leader as "unassailable" despite the turmoil currently engulfing the party.

Ross, who is both an MP and MSP, has said he wants the Prime Minister out of office as a result of the partygate revelations.

The exact nature of Covid regulation rule-breaking by the PM and his government remains subject to a report by civil servant Sue Gray, with Johnson telling MPs that although he did attend a wine-fuelled event in his Downing Street garden, he'd thought that was a work meeting and hadn't been told that it would infringe any of the rules he had put in place.

In response to Ross's remarks, Jacob Rees-Mogg, the leader of the House of Commons, said the Moray politician was a "lightweight" and "not a big figure".

And Michael Gove's take on the matter was that "he's in Elgin and the national Tory leader is in London".

READ MORE: If Boris Johnson goes, what next for Scottish independence?

On The Sunday Show, host Martin Geissler suggested to Kerr that Ross's position will be "unsustainable" if Johnson survives the scandal.

Kerr rejected that, saying: "Douglas Ross's mandate comes from the Scottish Conservative Party and its membership, it's a completely separate issue.

"Douglas is staying put. Douglas is there for good. Douglas is doing a great job. It's Douglas Ross's principled leadership that is, I think, shedding a very bright light on all of this."

Describing a touchline clash that took place during Ross's side work as a football official, he went on: "Douglas Ross's position is unassailable, unassailable. His mandate to be leader of the Scottish Conservative Party is completely divorced from anything that's happening in relation to the future the Prime Minister.

"I've got a favourite picture of Douglas as an assistant referee; Scott Brown, right up to his nose. Whenever I think of Douglas's strength, I think of that picture."

However, Kerr said Johnson – who has been condemned by Scottish Conservative MSPs – will not be able to cling on after Gray's report is published because more Tory MPs will submit letters of no confidence to Sir Graham Brady of the 1922 Committee.

He said: "The longer it takes for the Sue Gray report, the more detail there's going to be in it, the more investigation will have to take place and I think there's an inevitability to what happens next.

"It gives me absolutely, as you can imagine, no joy whatsoever to talk about a Conservative Prime Minister having to leave office but I think that is where this ends."