Workers at Bus Éireann look set to go on strike at midnight tonight amid a dispute over planned changes to their pay and conditions.
Staff say they could lose between three and four thousand euro a year to their salary but management say the cuts are necessary in order to ensure the company remains viable.
Up to 10,000 passengers will be affected by tomorrow's strike action and Bus Éireann says it will cost the firm €200,000 per day of strike action.
Both sides have indicated they are willing to engage in last-minute talks to avoid a strike.
But the General Secretary of the National Bus and Rail Union Michael Faherty says they are yet to receive an invite from the company.
"We won't be knocking on management's door asking for a meeting. They know we want to talk and they say they want to talk but it's a mystery why that hasn't happened.
"We represent 1,000 people and they won't be working. That's a certainty. I can't speak for other unions, so it's up to them what they do.
"It's an official strike and I can't see anybody passing an official strike."