Talks aimed at resolving the dispute at Bus Éireann are continuing at the Workplace Relations Commission, and are expected to go on for a number of hours yet.
Negotiators have been at the table since 11am in an ongoing effort to break the deadlock behind the strike.
The strike, which is now in its 16th day, is over cost-cutting measures at the company.
Sources at the talks say negotiations remain challenging with little progress being made.
Over 27 hours of talks were adjourned early yesterday morning without agreement.
Sources at the talks yesterday described progress as being "very slow", and while some tentative agreement was reached over improved efficiencies at the company, changes to pay structures sought by management remain a major stumbling block.
Bus Eireann talks resume at the WRC...it will be "the toughest day yet" according to SIPTU No comment from management #rtenews pic.twitter.com/dr26rVcApm
— Joe Mag Raollaigh (@joemagraollaigh) April 8, 2017
A SIPTU representative has said that "unless the company gets real, Bus Éireann won't continue to survive as we know it today".
Willie Noone also said "today will be the toughest day of all in negotiations". He said they have "dealt with a number of issues in broad strokes but now they're getting down to detail".
Minister for Transport Shane Ross has said he is hopeful that a resolution could be found in the coming days.
The strike has caused travel disruption nationwide as no Bus Éireann services, except school routes, have operated since 24 March.
