The SNP winning a majority of seats in either a Holyrood or Westminster election could be enough to spark independence negotiations if the UK Government fails to give the go-ahead for a second referendum by the autumn of 2020, two senior party members have suggested.
While First Minister Nicola Sturgeon has already earmarked the second half of next year as the best time for Scots to have another vote on independence, the UK Government is unlikely to give the necessary consent for a legally binding ballot to be held.
Both Boris Johnson and Jeremy Hunt, the two men vying to succeed Theresa May as prime minister, have made clear their opposition to Scotland having another vote on the issue.
In a bid to counter that, SNP MP Angus MacNeil and Christopher McEleny, the group leader on Inverclyde Council, have submitted a resolution for debate at the SNP conference in October.
It calls for a vote on independence to take place by autumn 2020, and adds that if the UK Government fails to grant a Section 30 order to enable this to happen, voters returning a majority of independence-supporting MSPs or Scottish MPs would give a mandate to the Scottish Government to start independence negotiations.
Mr McEleny said: "The people of Scotland have been consistently ignored by the UK Government. We want to hold a referendum to give people the choice between becoming an ordinary independent country or staying part of a UK that consistently imposes on Scotland policies and governments that we reject.
"However, despite a majority in Scotland wanting a referendum, the new UK prime minister looks set to reject this regardless of public opinion. That's why we need a way to ensure the democratic mandate of Scotland is respected - whether Jeremy Hunt or Boris Johnson like it or not."
However Scottish Conservatives hit out at the suggestion.
Maurice Golden, the party's chief whip at Holyrood, said: "There is no support among Scots for another independence referendum.
"But at every party conference, Nicola Sturgeon chooses to throw slabs of red meat to an increasingly rabid and hardline fringe in the SNP ranks.
"First she said there should be another divisive referendum by 2021. Now the SNP wants to break up the Union without even asking Scotland first."
An SNP spokesman said the party already had a "cast-iron mandate to give the people of Scotland the option of becoming independent in a referendum before the 2021 election".
He added: "The First Minister has made clear she believes this should take place toward the latter half of next year.
"Given the way Scotland's interests have been completely ignored in the Brexit process, and given the increasing likelihood that we will be dragged off the no-deal economic cliff-edge, it's no wonder support for the SNP and for independence is rising."