Trade unions have piled pressure on transport chiefs by warning drivers at Dublin Bus and Irish Rail will vote on strikes in solidarity with Bus Eireann workers.
Siptu members at the other two companies would be balloted on industrial action despite a 48-hour stay on the walkout and pickets to allow for talks with mediators.
Bus Eireann employees and management have been locked in dispute for months over the company's plan to slash five million euro off the pay bill in a bid to stem massive losses.
Siptu shop stewards from Bus Eireann, Dublin Bus, and Irish Rail from the CIE Group said the vote would be a sign of solidarity with counterparts in the state controlled bus firm.
Siptu spokesman WIllie Noone said: "Workers across the three companies that make up the CIE Group share a concern about management attempts to cut staff pay and conditions of employment."
Siptu's other ballot for strike action involving its members at Bus Eireann will be announced on Thursday but it is likely to call for a walk out.
Mr Noone said: "In a show of solidarity with their colleagues in Bus Eireann, shop stewards at the other two CIE companies have requested permission to also ballot for industrial action. Our members are adamant that it is made clear to management that any attempt to enforce cuts on workers in Dublin Bus and Irish Rail will be resisted."
Bus Eireann has warned it needs to make 5m euro payroll savings or it will go out of business. It is in talks with the National Bus and Rail Union at the Labour Relations Commission (LRC) in a bid to secure a deal to prevent a return to picket lines which stopped services nationwide on Sunday and Monday.
Mr Noone added: "Workers at the CIE Group of Companies share a deep concern in ensuring the future viability of the Group is secured. However, cuts which only focus on reducing the pay and conditions of employment of workers while seeking no similar contribution from highly paid management grades will not be accepted."
Bus Eireann said the vast majority of its services were back to normal on Tuesday after the two-day stoppage. Management and unions have until Friday morning to strike a deal at the LRC. The strike cost the company an estimated 400,000 euro over two days.