RMT union members and supporters were set to lobby the Scottish parliament on Wednesday of this week,
They want Clyde and Hebrides Ferry Services to stay in public ownership.
The lobby coincides with a debate on the tender process for the services, which could see outsourcing giant Serco take over from public sector operator CalMac.
CalMac workers struck earlier this year to demand assurances on their conditions.
RMT said Serco are “specialists in failure” with an appalling record.
The union is in dispute with Serco over a range of safety and maintenance failures in a separate dispute on its Caledonian Sleeper rail franchise worth £800 million.
It is balloting members for industrial action.
25 November, 1.30pm
The RMT union suspended a strike of members working on Stagecoach buses in Norfolk planned for Tuesday of this week.
The walkout was called in a dispute over pay and conditions. Workers voted for the walkout by nearly nine to one.
But the union suspended the action to consider a new pay offer from bosses.