Fianna Fáil leader Micheál Martin has said what he called the “big lie" at the heart of the fiscal treaty No campaign needs to be exposed.
He insisted there was no foundation to the assertion by Sinn Féin and others that €5 billion extra would have to be taken from taxpayers in the event of a Yes vote.
"If anything a no vote would increase the amount of cuts one would have to make, increase the adjustments to the budget. A Yes vote actually means less austerity, not more and that's the big lie at the heart of the No campaign to date and it needs to be exposed for what it is," Mr Martin said.
He said the latest opinion poll reflected his perception that there was a "significant don't know element" in the electorate, although there were more "definite Yeses than define Nos".
He said Fianna Fáil had consistently been one of the most pro-European parties. While the situation in Greece was worrying, "we need calm heads. We need to hold our nerve as a country."
Mr Martin was speaking at the launch of his party's national strategy on youth employment this afternoon.
Fianna Fáil's spokesman on children and youth affairs Charlie McConalogue said the party was proposing a range of "sector specific" initiatives to provide young people with the best possible chance of starting a career in Ireland.
"Our proposals are realistic and affordable. We estimate that this plan will require an initial investment of €52 million, but the cost of not taking any action is far greater," Mr McConalogue said.
The strategy includes a proposal to establish a programme providing 1,000 internships in the IFSC and a proposal to train 100,000 young jobseekers with ICT skills over the next four years to address the skills shortage in the technology sector.
