Micheál Martin says Fianna Fáil will offer the public a "real alternative" at the next election.
He's told his party's Ard Fheis that Fine Gael and Labour campaigned against all of Fianna Fáil's policies - but then implemented them anyway.
His opening speech focused heavily on health, criticising the government for allowing the numbers on trolleys to increase.
And he says Fianna Fáil will give voters an alternative to what he sees as broken promises.
"They voted and campaigned against all of the key measures which stabalised the budget and in government it took them over three years before they produced even the most basic plan of their own," he said.
"What we’re going to do is to set out a real alternative to the spin, to the broken promises, to the growing inequality and unfairness of Fine Gael and Labour," he said.
Fianna Fáil has also voted to change the way they elect the party leader.
Up to now only TDs had a vote to elect the leader.
But now a new college system will see ordinary members have their say, as well as Senators and MEP's.