The Scottish Secretary has indicated he could quit if the UK remains tied to EU fishing policies and quotas until 2022.
David Mundell and the other 12 Scottish Conservative MPs wrote to Theresa May threatening mutiny if fishermen and women remain tied to the Common Fisheries Policy (CFP) past December 2020.
With the EU chief negotiator Michel Barnier suggesting the transition deal could be extended by two more years, Mr Mundell put his foot down.
“I’m very clear we can’t extend the period and include the Common Fisheries Policy in that extension,” he said.
“I could not support that. I’m not playing into the resignation soap opera - what I’m focused on is outcomes.”
Mr Mundell insisted he was trying to get the best deal possible for Scotland and attacked the SNP for “backing no deal”, which he said was the worst possible outcome, at the latest joint ministerial council (JMC) meeting today.
Mr Mundell accused Scottish Brexit Secretary Mike Russell of changing his position on a Brexit deal in the meeting to pursue an “independence agenda”.
He said: “The big change today was after 14 meetings where he had previously said what a bad outcome no deal would be for Scotland and the UK, Mike Russell said today SNP MPs would be backing no deal.
“I think it’s a very serious situation and it will be particularly when we get to the meaningful vote.
“I hope when we get to that point people won’t be playing politics and looking for what outcome is most likely to get us an independence referendum or what outcome is most likely to get us a general election.
“I hope they will think what is in the best interest of people, of jobs, of the economy of Scotland and the UK.”
Mr Mundell also appealed to his Scottish Tory colleagues, three of whom are ERG supporters, to back the Prime Minister because “there isn’t some purist version of Brexit available”.
Speaking as he left the JMC, Mr Russell said Mrs May’s deal was “an emergency” that “must be stopped”.
“It’s an emergency for all the nations in in these islands to stop this deal,” he said. “This deal is a disastrous deal.
“Mr Mundell knows the damage this will do to Scotland - it’s beyond belief and in those circumstances the first thing to do is to stop this deal.
“It is not this deal or nothing - that’s nonsense that is being sold vigorously by some of the people in that meeting.”
Mr Russell said if the SNP was unable to stop the “unacceptable deal” then a second Scottish independence referendum should follow as there was no greater illustration for independence than Brexit.
“The wrong thing to happen here is for Theresa May to dig in, which she has already done, and just say she is the only one that has the answers,” he said.
“She is not and it’s important to say that.
“If the unacceptable deal goes through - and I never predict these things - there will be substantial economic damage and then I’m happy to say we will have to say to the people of Scotland ‘make your choice’.”
Scottish opposition leaders have previously rounded on Mr Mundell as “unconvincing”, with shadow Scottish secretary Lesley Laird calling on him to quit to “retain any shred of credibility” and Scottish Lib Dem leader Wilie Rennie telling him “nobody was fooled”.