SIPTU members employed in RTÉ have voted overwhelmingly in favour of balloting for industrial action if there is any further outsourcing of production or roles at the broadcaster.
In a preventive ballot, members voted 85% in favour of the proposals.
SIPTU represents around 600 RTÉ staff.
"This strong ballot result demonstrates the determination of SIPTU members in RTÉ to defend public service broadcasting while also ensuring that workers' voices are heard and respected," said SIPTU Services Divisional Organiser Adrian Kane.
"Unfortunately, if management continues on its current course, it is clear our members will engage in industrial action to protect the future of the station," Mr Kane said.
In February, SIPTU members in RTÉ voted no confidence in RTÉ's New Direction Strategy, which the union said would result in the endless outsourcing of jobs and deal a fatal blow to public service broadcasting.
In March, members of the National Union of Journalists (NUJ) in RTÉ also voted no confidence in the RTÉ strategy.
RTÉ has previously said it believes that the five-year strategy, now in its second year of implementation, offers the best way forward to secure the future of Ireland's national public service media and give more to Irish audiences in a much changed media landscape and with rapidly evolving audience habits.
"This strategy was published following extensive consultation with the public, RTÉ staff and a wider group of stakeholders," an RTÉ spokesperson said.
"The vast majority of staff supported the need for RTÉ to evolve as outlined in the strategy during this consultation process.
"We continue to remain available to meet with the unions, as we have done, to progress these and other relevant issues," they added.
