The Rail, Maritime and Transport union (RMT) is expected to name dates for walkouts and other action.
It would go ahead if talks arranged for tomorrow at the conciliation service Acas fail.
The move comes a week after conductors voted by three to one for stoppages.
The ballot result also showed a majority of all conductors supported action.
The union will have to give seven days’ notice of any strike.
ScotRail is drafting in staff from other train operators to cover during a strike, who the RMT has called a “scab army”.
The dispute is over plans to change conductors’ duties aboard a new fleet of electric trains being introduced across the Central Belt from next year.
Drivers would take over control of doors and passenger safety.
Conductors would be left to check tickets, but lower-paid ticket examiners would perform that role on some services.
ScotRail sent proposals for the changes in a letter to staff but has not presented them formally to the RMT.
It said it had now withdrawn the letter, but the RMT said it was clear the firm still intended to go ahead with the plans, to save money.
A ScotRail spokewoman said: “We believe the solution to this dispute lies in talks, not strikes.
“We’re look forward to getting round the table again for continued talks with Acas and RMT on 15 June.”