The Conservative Party is in open civil war today after Jacob Rees-Mogg labelled the Scottish Tory leader Douglas Ross a 'lightweight figure'. Mr Ross yesterday called on Boris Johnson to quit over the Number 10 party row as he said the Prime Minister's position is 'no longer tenable'. But Mr Rees-Mogg defended the PM and criticised Mr Ross, telling the BBC that the most senior Tory in Scotland is not a 'big figure'. The comments are likely to worsen a growing divide between the Scottish Tories and their colleagues in London. The SNP immediately seized on the row as it claimed the Conservative civil war is 'making the case for independence'. The Conservative Party is in open civil war today after Jacob Rees-Mogg labelled the Scottish Tory leader Douglas Ross a 'lightweight figure' Mr Ross yesterday called on Boris Johnson to quit over the Number 10 party row as he said the Prime Minister's position is 'no longer tenable' Conservative MSPs at Holyrood are in open revolt against the PM after heaping pressure on him to resign. Mr Ross, the MP for Moray, said Mr Johnson should quit after he admitted attending a Downing Street party during lockdown. He told STV News yesterday afternoon: 'I said if the Prime Minister attended this event in Downing Street on May 20, 2020, he could not continue as Prime Minister so, regretfully, I have to say his position is no longer tenable.' Politico reported that 26 of the 31 Scottish Tory MSPs have now gone on the record to call for Mr Johnson to go while the BBC's Newsnight programme said all 31 believe the PM has to quit. But Mr Rees-Mogg went on the offensive last night as he told LBC Radio: 'I don't think it is a surprise that Douglas Ross takes this view, he has never been a supporter of the Prime Minister. 'He has constantly made disobliging comments about the Prime Minister. I listen to the Scottish Secretary, to Alister Jack.' Told that Mr Ross had backed Mr Johnson during the Tory leadership contest, Mr Rees-Mogg said: 'People do sometimes vote for people in leadership elections who don't live up to expectations. 'I don't think Douglas Ross is a big figure. I think Alister Jack is a really serious and senior figure.' The Commons Leader then doubled down during an interview on Newsnight as he said: 'I would actually say that the Secretary of State for Scotland, who is a big figure, is very supportive of the Prime Minister, has made that absolutely clear. 'Douglas Ross has always been quite a lightweight figure so I don't think that his… I think the Scottish Secretary is a much more substantial and important figure in this.' The comments prompted an immediate backlash as the atmosphere within the Conservative Party continued to sour. Conservative MP Andrew Percy hit back at Mr Rees-Mogg, reportedly telling the BBC that 'Douglas Ross has far more understanding of the lives and views of normal people... than some of those attacking him ever will'. Mr Ross said Mr Johnson should quit after he admitted attending a Downing Street party during lockdown . The two men are pictured together in November 2019 during the general election campaign Mr Percy said that Mr Rees-Mogg 'prides himself on a carefully crafted reputation of over the top politeness' but that he 'might need to practice his act a little more in the mirror tonight after his personal attack on Douglas'. The SNP's Westminster deputy leader, Kirsten Oswald, said: 'By dismissing their Scottish branch office as a bunch of "lightweights" and nobodies, the Tories are revealing their disdain for Scotland and making the case for independence. 'Not only is it deeply humiliating for Douglas Ross but it is a telling insight into the arrogant and dismissive attitude that the Tory government has towards Scotland as a whole.' Mr Ross's predecessor as Scottish Tory leader, Ruth Davidson, backed his decision to call for Mr Johnson to quit, describing it as a 'tough call to make, but the right one'. Jackson Carlaw, another former Scottish Tory leader, also demanded Mr Johnson go, along with other Conservatives MSPs. He tweeted: 'Given that the PM has now confirmed he attended a rule-breaking gathering, he has lost the confidence of the country, so I believe Douglas has made the right call and that the PM should stand down.' All rights reserved for this news site (dailymail) and under his responsibility