FINE Gael has warned public servants their pay will be under threat unless it slashes the state workforce by 30,000.
But it assured the main public service union, IMPACT, it "definitely won't" impose compulsory job losses if it wins the election.
The party outlined its policy in a letter after the union asked each party to detail their proposals on the key issues facing workers.
The letter also revealed plans that appear to effectively dismantle legally-binding minimum wage rates in some sectors.
It said it would allow employers and unions to negotiate deals on a local level that would "exempt" them from minimum statutory pay rates, known as Employment Regulation Orders.
This policy would most likely alarm unions, which have launched a campaign to protect these rates that cover sectors including retail, hairdressing and contract cleaning. Fine Gael also told the union it backs the Croke Park agreement, which does not allow the Government to cut pay or pensions before 2014.
However, it warned that pay -- which makes up a third of government spending -- will be on the line unless it reaches its target in cutting numbers.
"The only way to protect public service pay is to reduce staffing levels," stated the Fine Gael document.
"We have been clear that Fine Gael would seek an additional voluntary reduction of 18,000 in staffing levels across the public service while protecting front line services.
"We believe these can be met from voluntary redundancies and natural retirements. This is the only way public service pay can be maintained."
Of all the parties, Fine Gael is seeking the largest cut in the 305,000-strong public-service workforce. It wants a reduction of 18,000 public servants on top of the target of more than 12,000 already set by the outgoing Government.
Labour is planning the second deepest cut, of 18,000, while Sinn Fein has no plans to cut staff.
Fine Gael did not commit itself, though, as to whether it would reduce public servants' pay or pension entitlements.
It said it "does not want" to further reduce pay and pensions, but "definitely won't" impose compulsory redundancies. In its response, Labour claimed Fine Gael's redundancy plan would take two teachers from every primary school and one in every six nurses out of the public service.
Last November, the Fianna Fail/Green coalition committed itself to cutting the public-sector workforce by 2014.
Meanwhile, in its submission to IMPACT, Sinn Fein claimed Fianna Fail, Fine Gael and Labour supported compulsory redundancies and pay cuts for public servants.