Nigel Farage's newly formed Brexit party looks poised to take one or possibly two of Scotland's six Euro MEP seats in Thursday's vote and the First Minister says hardline Bexiteers are "stepping up their efforts."
The SNP leader has now issued a call to all pro-Remain voters to get behind her party as the "strongest anti-Brexit voice."
Ms Sturgeon has now issued an open letter targeting around one million voters ahead of the poll.
"In Scotland the best way to bring about that outcome is to vote SNP. We are by some distance the strongest pro-European party, therefore a vote for the SNP is the most effective means to ensure remain supporting MEPs are elected.
"On the other side of the debate, those who favour an extreme Brexit – a No Deal outcome – are stepping up their efforts.
"That means there is a real danger we will all be at the mercy of further in-fighting among hard-liners at Westminster for years to come, so if ever there was a time to make a stand for a better future it is now."
The Brexit referendum in 2016 saw a majority (62%) of Scots vote to Remain in the EU, but the weight of votes south of the border swung the outcome in favour of leave.