A parliamentary motion seeking support to call for permission for a second ballot has been published at Holyrood.
The Scottish Government wants a referendum to take place between autumn next year and spring 2019, when it says there will be clarity over the outcome of the Brexit negotiations.
Prime Minister Theresa May has said “now is not the time” for another vote and has indicated that the UK Government would reject the SNP’s preferred timetable.
The details of the order should ensure that Holyrood can legislate for a vote “at a time, and with a question and franchise, determined by the Scottish Parliament, which would most appropriately be between the autumn of next year, 2018, when there is clarity over the outcome of the Brexit negotiations and around the point at which the UK leaves the EU in spring 2019”, the motion adds.
Although Ms Sturgeon leads a minority government, the support of the Scottish Greens means the motion is expected to be passed on Wednesday following a two-day debate.
“If MSPs pass this motion this week, then the Prime Minister’s position of blocking a referendum and forcing through a hard Brexit without giving the people a choice will be democratically indefensible,” Ms Sturgeon said.
“I agree with the Prime Minister when she says that there needs to be clarity about the implications of Brexit before the people of Scotland can choose - that is precisely why we are proposing to hold the vote at the point where we know, through the Prime Minister’s own statements, we will have that clarity.
“A clear precedent was set in 2012 when the UK government said that the 2014 referendum should be ‘made in Scotland, by the people of Scotland’. That is the principle that they must again hold to.
“Ultimately, this crucial decision over our future should not be made unilaterally by me, or by the Prime Minister - it should be made by the people of Scotland, and I call on Parliament to give the people that choice.”
“Eighty five per cent of our fellow citizens voted in the first referendum, and they voted by a very clear majority to remain in the United Kingdom,” she said,
“In 2014, this country was divided more than at any time in our recent history.
“We don’t want to go back to that. Those who voted to leave the UK and the majority who voted to remain in the UK don’t want to back to the divisions of the past.”