Appealing to workers on behalf of the executive of the Irish Congress of Trade Unions to come out and vote Yes, the general secretary of the ICTU, Mr David Begg deplored claims that Nice was a threat either to jobs or public services.
"I want to nail the big lie on the black and red Nazi-style posters that voting No will save Irish jobs," he told a press conference in Dublin. "We run a real risk of losing jobs by voting No. We can help to make jobs secure by voting Yes.
"Extending EU standards of wages and conditions and workers' rights to workers in central and eastern Europe will remove the incentive for businesses to move their operations from countries like Ireland to countries with cheaper labour and working conditions."
Mr Begg was joined at a Dublin press conference yesterday by the Labour Party leader, Mr Ruairí Quinn and its president, Mr Proinsias De Rossa MEP, and Congress's assistant general secretary, Ms Joan Carmichael, in denouncing those, claiming to be on the left, who argued that globalisation could be fought by rejecting the EU.
Mr Begg said the challenge was to defend the European social model and the European idea of environmental sustainability against the largely American-inspired globalisation model based on laissez-faire capitalism and shareholder values.
Mr Quinn said that 30 years of experience had shown that the workers' movement benefited from more not less majority voting in the EU.
It had been Margaret Thatcher, he said, who had been able single-handedly to hold up the Social Chapter with her veto. That was true on many issues of concern to workers.
Mr De Rossa asked why the Greens clung to the veto in the EU when key environmental proposals, like proposals for a carbon tax, had been blocked for years by veto-wielding member states.
He described the "single thread" that linked that party to Sinn Féin, Mr Anthony Coughlan, Mr Justin Barrett and other No campaigners as a "poor-little-Ireland mentality" and "insular nationalism".
The alternative, Ms Carmichael argued, was solidarity, like that displayed by the workers in Europe when Irish women were fighting for maternity leave.
Like the sort of solidarity we should display to the workers of the accession countries, she said.
Mr Begg rounded on those who claimed that Article 133 of the treaty, providing for an EU role in international negotiations on trade deals in services and intellectual property, had anything to do with privatisation.
Noting that key areas such as education, health, culture and the audio-visual sector had been exempted from the provisions, Mr Begg said that anyway, no state could be forced by the EU to alter the ownership of services.
Mr De Rossa said the No claims were a "blatant lie" born out of panic that they are losing the argument.
Insisting that Labour was determined to protect public services, Mr De Rossa said it was crucial to understand that "if Irish services are privatised, it is the Irish Government that makes the decision".