Opponents of the Nice Treaty must explain the economic reasons why people should vote No in the upcoming referendum, the Taoiseach, Mr Ahern, said yesterday.
"There is a very strong economic case for voting Yes to Nice; isn't it time the No side set out the economic case for voting No?" he asked.
Mr Ahern said unhindered access to the European market was a huge attraction for foreign investment in Ireland. "A perceived retreat through a No vote from full commitment to the EU single market and to the expansion of that market by enlargement would give a negative signal to foreign investors," he said.
Such a result "would be exploited by our competitors" for foreign investment. "Ireland already must compete with our existing EU partners for such investment and does so very successfully," the Taoiseach added.
"It will be up to us to meet any new challenges that may arise.Given our very successful track record and the continuing upskilling of our workforce, we should be able to respond well to any new challenges."
A second rejection of the treaty would mean that Ireland would carry "considerably less weight in future discussions of critical importance to our economy".
He went on: "We have been enormously successful in protecting our interests in key areas like CAP, structural and cohesion funds and taxation because we were perceived as centrally involved in Europe and able to forge alliances and be listened to on that basis.
"A rejection will dilute Irish influence at a time when key decisions are looming, including reform of the Common Agricultural Policy, the next WTO round and the post-2006 EU budget. In this context we should remember that Ireland still receives substantially more from the EU budget than it pays in," he added.