The Irish Medical Organisation (IMO) will begin it's annual conference in Kerry this afternoon. It is expected that the proposed cuts under Croke Park Two will top their agenda.
The union are one of many who have called on their members to vote against the extension to the deal.
They have organised a series of national meetings organised jointly with the INMO, CPSU, UNITE and the 24/7 Alliance.
The IMO says the proposals will "significantly" increase weekly working hours and reduce take home pay and "at the same time do nothing to generate growth in the economy".
Their key objections to the proposals focus on what they say are the imposition of longer working hours, proposals to freeze and delay normal increments, significant pay cuts for IMO members and a refusal to remove "the Two Tier workforce for new and, in certain circumstances, existing Consultants".
Doctors are due to debate hundreds of motions over the next 3 days. The IMO is also expected to discuss the issue of abortion, after the Health Service Executive (HSE) report into the death of Savita Halappanavar.