A second independence referendum is "unlikely" to happen within Nicola Sturgeon's preferred time frame, a former SNP senior staff member said.
Kevin Pringle also warned that, if a vote on leaving the UK is held before the end of 2023, the SNP's goal of increasing support for independence may be "undermined".
The First Minister has repeatedly said her intention is to hold indyref2 by the midway point in this Holyrood term - although the UK Government remains hostile to such plans.
