The National Bus and Railworkers Union has said it will be attending talks today "in resolution mode".
Discussions are planned at the Labour Relations Commission as part of the drive to avert another round of strike action on bus services next Friday and Saturday.
Siptu will also attend the negotiations in Dublin this afternoon.
Dermot O'Leary of the NRBU said he is willing to work on the dispute, which centres on 10% of routes being put out to tender.
"There's enough room here for public companies and private companies to work side by side," he said.
"The reality here is that the NTA to date have been intransigent in relation to matching growth - which they admit is there - marching growth with that private entry.
"And they insisting on stripping out 10% of publicly-owned bus routes."