Bus drivers say they are seeking the same pay increases that were recently awarded to Luas drivers.
It comes after a tram strike was averted yesterday following last minute marathon talks.
Luas drivers want to be paid on the same scale as drivers at Irish Rail.
While bus drivers want to also benefit from any pay increases given to Luas workers.
But Dermot O'Leary, general-secretary of the National Bus and Railworkers' Union (NBRU), says they will ballot for industrial action if necessary.
"We have had a pay claim in with Dublin Bus and Bus Éireann for a considerable period of time - nearly 18 months at this stage - and they were progressing very slowly" he told Newstalk Breakfast.
"The bus drivers are around a lot longer and the bus drivers carry...about 50,000 passengers a day - the bus is known as the 'work horse' of the industry".
"We want the same rate of pay that the Luas drivers now have at the top of their scale".
Mr O'Leary said while he did not have the figure in front of him, "but whatever the Luas got, of course bus drivers will want it".
The NBRU is going to the Workplace Relations Commission (WRC) with Dublin Bus next Wednesday.
On the possibility of strike action over their pay claim, he replied: "Our intention is never to discommode the public - obviously if something doesn't give here we will have to consider that".
