SIPTU has warned it will pursue private sector wage increases if the Government reduces the deficit below the target for next year required under the Troika's bailout plan.
SIPTU President Jack O'Connor said the union was totally opposed to doing "one cent more than the absolute minimum" required to secure the 5.1% deficit target for 2014.
However, he warned that if that happened, SIPTU would urge the private sector committee of the Irish Congress of Trade Unions to spearhead what he called "a radical new drive for pay increases across the economy".
Addressing his union's biennial conference in Dublin, Mr O’Connor said the only way of meeting the 2015 deficit target of 3% was by growing the economy by 5.3% over the period.
He said this could only be achieved by boosting domestic demand, which has fallen by 24% since the crisis hit in 2008.
He said if the Government insisted on "over-egging the pudding" to impress the financial markets, there was another way to stimulate domestic demand - by substantially increasing pay.
He noted that SIPTU has sanctioned industrial action in almost 40 instances over the last two years - and warned that the union would give its absolute and fullest support to members who vote to take industrial action to advance their interests.
Mr O'Connor also called on Fine Gael to lift what he called its "veto" on a tax contribution from the wealthy so that the biggest element of the adjustment would be funded entirely by those who can most afford it.
He defended Labour's role in government and claimed that if Fine Gael had a single party overall majority, the country would have suffered an additional €1.2 billion in cuts to date.
Mr O’Connor also said the wage setting mechanisms protecting 200,000 lower paid workers would not have been reinstated, and more State assets would have been sold off.
However, he said this did not mean that SIPTU felt that the budgets under the Government were fair.
However, they equally did not subscribe to the simplistic view that it was all Labour's fault, noting that 60% of voters in 2011 had voted for right wing parties.
He said based on opinion polls, those parties would secure a majority again if there were an election now.
Mr O'Connor also appealed for unity on the left, saying he disagreed with those who described Sinn Féin economics as "fantasy economics".
He defended what he called the union’s "rear-guard strategy" over the past five years.
He said it was like being accosted by a band of armed robbers on a remote country road on a dark, wet winter's night demanding your car on pain of your life.
He said you could mix it with them in the hope of overcoming them, or give them the car and suffer the misery of carrying on on foot.
He said you could get another car but you could not get your life back.
He said noone could reasonably accuse anyone of being unprincipled for making such a decision.