SINN FÉIN is to blitz households with half a million newsletters urging a no vote in the Lisbon Treaty referendum.
The party is also planning a series of regional public meetings as part of a campaign it says will be approached "in general election mode".
Kicking off the campaign in Dublin, MEP Mary Lou McDonald insisted there was no contradiction in being pro-Europe but anti-treaty, and denied the party was a eurosceptic.
"People know Ireland’s place in the EU is secure and that it is possible to support the EU and be against the Lisbon Treaty," she said.
Ireland is the only country in the EU that will be holding a referendum on the treaty, which aims at streamlining the union’s expanding bureaucracy by ending the automatic right of smaller countries to have a commissioner, rationing votes on the Council of Ministers and centralising decisions on foreign policy.
Sinn Féin, the only anti-treaty party in the Dáil, says the treaty will damage democracy and accountability within the union, further erode Ireland’s neutrality, encourage privatisation of public services and limit member states’ right to vote on further treaties.
Ms McDonald said a no vote would force the EU back to the drawing board.
The party has published what it calls "an alternative guide to the Lisbon Treaty" that sets out its objections, and says it will be distributed by the Forum on Europe along with its official information pamphlets.
Meanwhile, Minister for Foreign Affairs Dermot Ahern urged a yes vote, arguing the country’s interests are better served by a unified European approach.
"Our opponents — when you peel back the rebranding, remodelling, refinancing — are the same old groups, the same tired old interests retelling the same old myths," he said.
The Government has not yet set a date for the referendum but it is expected to be held before the summer.