Taoiseach Enda Kenny has urged his backbenchers to use parliamentary party meetings to raise their concerns about the Budget.
Mr Kenny was speaking after eight Fine Gael TDs challenged the Government's policy on the Croke Park Agreement in a newspaper article.
In an article in the Irish Examiner, the group called for cuts to the increments and allowances of higher-paid public servants, saying these two areas are not part of the agreement.
They said pay increases must be put back on the table to correct the budget deficit.
Fine Gael Galway West TD Seán Kyne, who is one of the eight TDs who wrote the article, said he believes it does not make any sense to pay increments while borrowing and cutting back frontline services.
Speaking on RTÉ's Morning Ireland, he said ministers and politicians seem afraid to tackle the issue because of fears of a union backlash.
He said there is a tough Budget ahead where more cuts are required, but "as long as we are continuing to abide by all the rules and regulations of Croke Park ... then it's more difficult to defend the very difficult cuts we are going to have to implement".
The other seven TDs to express doubts about the savings are Sean Conlan, Paul Connaghton, Pat Deering, Brendan Griffin, Noel Harrington, Anthony Lawlor and Eoghan Murphy.
Mr Deering said the TDs were talking about people at management level who earned in excess of €80-90,000 a year.
The Carlow/Kilkenny TD said the Government was due to pay out €170m in allowances and increments next year and this was not sustainable.
He said there was currently a "once in a lifetime opportunity" for serious reform, and he and his colleagues felt the time was right to publicly call for the issue to be be looked at.
Taoiseach Enda Kenny said there is a real opportunity to have serious moves about reform and cost of the public service.
He said Croke Park brought us to this point without industrial strife and he wants now to move to a point where "we shove the agenda more forcefully, more ambitiously with a view to getting the maximum" out of it.
Meanwhile, Chairman of the Croke Park Implementation Body PJ Fitzpatrick rejected claims that savings made under the agreement are being overstated.
Speaking on RTÉ's Morning Ireland, Mr Fitzpatrick said he was entirely satisfied with the accuracy of the €810m figure for savings in the pay bill.
He said formulas for additional or notional savings have not been included and it was in nobody's interest to use inaccurate figures.
The Department of Public Expenditure and Reform has also rejected claims that the savings were overstated.
Elsewhere, INTO General Secretary Shiela Nunan said there has been an attempt over recent days to put words in Mr Fitzpatrick's mouth.
Speaking on Today with Pat Kenny, Ms Nunan, who is also on the implementation board said that she is "absolutely, entirely 100% clear" on the point that increments and allowances form part of core pay.
Ms Nunan said that her position is shared by her colleagues in the trade union movement.
Minister for Communications Pat Rabbitte said the Government had to proceed with great care in this area because these allowances have grown up over many decades and many are part and parcel of the pay of people concerned.
Responding to reports that the Troika is unhappy with the Government cutting services while not tackling vested interests, he asked do they want the Government to slash people's core pay and conditions without consultation.
Mr Rabbitte said Ireland has been complying with its targets and will meet its obligations for the remainder of the programme, and the Government intends to get back to the markets by the end of next year.
Government urged to consider wealth tax
The Government has been urged to consider increasing tax on the better off in the Budget.
Two Labour TDs who have lost the party whip, Patrick Nulty and Tommy Broughan, and MEP Nessa Childers said they want a shift away from austerity towards a pro-growth agenda.
They are proposing a wealth tax, a financial transaction tax, and a 48% income tax rate on those earning over €100,000 a year.
Mr Nulty said Fine Gael would have to be willing to listen to constructive proposals.
Mr Broughan said he hoped his Labour colleagues, especially the five in Cabinet, would listen to what they were saying.