The largest union of Bus Eireann workers has confirmed it will take all-out strike action.
The National Bus and Rail Union (NBRU) voted to reject cost-cutting recommendations from the Labour Court.
A spokesman said a ballot was held on whether to support the measures, which will take effect from May 12 and could see some workers lose up to 4,000 euro a year in pay.
He said 83% of the 820 votes cast rejected the recommendations, meaning workers will strike from Sunday.
"Rejecting the Labour Court's recommendations means we have re-invoked a previous mandate reached in January to strike," the spokesman said. "No one knows when it's going to finish. All we can hope is that some sort of an agreement is reached, because these workers cannot afford the pay cuts facing them."
Earlier, Tanaiste Eamon Gilmore warned that Bus Eireann risks going out of business and workers losing their jobs if the crucial savings are not made. He said the company had lost 27 million euro over the last five years and would not be financially viable if it does not impose cuts.
Bus Eireann faces annual losses of 11 million euro and has been advised by the Labour Court to make five million euro in reductions in its pay bill. It has recommended a 20% cut to a range of allowance and expense payments, a reduction of overtime rates, longer working hours and a cut in shift payments.
The NBRU spokesman said there was a lot of anger among workers. "The 83% rejection of the Labour Court recommendations means we can do nothing but strike," he said. "That's a reflection of the anger that's out there. It's such a pity because all these men want to do is work and earn a living."
Meanwhile, a Bus Eireann spokesman called for the union to outline details of its strike to ensure minimum disruption for customers.
The company spokesman said: "We have received no detail from any of the trade unions on what action they are planning to take from May 12. It is critical for our customers that the trade unions inform the company of this as soon as possible so that we can let our customers know if and what level of disruption there will be to their services."