Minister for Finance Brian Lenihan has said Ireland's relationship with Europe will not remain the same if the Lisbon Treaty is not passed next month.
Speaking this evening, the minister said the treaty was crucial for a return to economic growth, and that a No vote would damage the Government's hand in its dealings with the European Union.
Speaking on RTÉ Radio's Drivetime, Ryanair CEO Michael O'Leary has said a Yes vote in the Lisbon treaty referendum would help the Irish economy.
He also said he would have no problem debating the treaty with Libertas founder Declan Ganley, whom he called a 'failed politician'.
But Sinn Féin has said Ireland would lose influence in Europe if the treaty comes into force, and the Irish Anti-War Movement said the treaty would promote the arms industry.
Earlier, the Standing Committee of the Catholic hierarchy said the Lisbon Treaty does not undermine existing Irish legal protection for the unborn.
In a statement it said a Catholic can, in good conscience, vote Yes or No.
Maynooth's Standing Committee comprises 12 of Ireland's 32 serving Catholic bishops and includes all four archbishops.
They said the treaty's pooling of sovereignty in specific areas could strengthen the common good, although they warned that this must not be allowed to weaken one of the EU's core principles to date - namely that a central authority should perform only those tasks which cannot be performed effectively at a local level.
On abortion, they reassured believers that the Treaty does not undermine existing legal protections in Ireland for the unborn.
They also condemned any material which misinforms voters as having no place in church buildings or grounds.
Separately, leading voices in three Protestant churches have warned that a No vote would increase Ireland's isolation with implications for its future in the current economic crisis.
The Church of Ireland's Specialist Committee on Europe, the Methodist President and the Quakers' Clerk effectively urge a Yes vote, saying a rejection of Lisbon would, among other things, indefinitely hinder enlargement thus denying to others the enormous benefits Ireland has enjoyed since joining the EU.
Meanwhile, a poll carried out by Red C for the Farmers Journal and IFA shows that over 80% of farmers will vote Yes in next weeks' Referendum (69% will vote Yes, 15% No and 16% are undecided).
Earlier, David Begg, General Secretary of the Irish Congress of Trade Unions, urged workers to support the Lisbon Treaty, saying things are bad enough in the country as they are, without making them any worse.
He claimed it would be 'suicidal' from the point of view of union members to reject the treaty.
Elsewhere, Eamon Gilmore, Labour Party leader told the Oireachtas European Affairs Committee, that playing an active role in a reformed EU is in the country's interest.
He said that there is much to be gained by the Irish people in supporting the Lisbon Treaty.
Separately, the Supreme Court has dismissed an appeal by Tipperary farmer, John Gerard Burke, to the ruling not to allow him to challenge the legality of a second referendum on the Lisbon Treaty.
The Court held there was nothing in the Constitution to prevent the holding of a referendum, even if that proposal has already been put to the people in a previous referendum.
Ireland votes on the second Lisbon referendum on 2 October.
For more: RTÉ.ie/Lisbon