The Tánaiste has said she did not believe that, in last year's Nice referendum, people really wanted to say No to new member states joining the EU.
Strongly advocating a Yes vote in the referendum, Ms Harney said: "I do not believe we want to turn away the very countries who had suffered for 45 years under internal totalitarian rule, dominated by an external super-power and prevented from acting in accordance with their European heritage."
She added that she did not think people wanted to say No to the jobs and investment that arose from working in the European single market. "I don't think we wanted to say No to Ireland having influence and a role in the community of nations that is the European Union. I don't believe that the Irish people really want a sudden about-turn in our role in Europe."
She warned that if the Irish people rejected Nice again, they would effectively, and much more clearly, be saying No to all those things.
"This is how our decision will be read among our fellow member states, among applicant countries and among international investors in Ireland."
She said last year's result was a fact which was not to be rejected or ignored or undermined.
"We have stopped and listened to what it meant. It is a plain fact that a lot of people did not vote at all last year. I accept that some people voted No for this reason and I accept my part of the responsibility for it, and, also, the responsibility to act in the national interest in response to it."
She added that last year's vote reminded the Government and political leaders not to assume too much, nor to presume too much, on the assent of the people "whom we serve, after all".
"And I can say, the message has got through, here in the House, in Government Buildings, in Brussels and around European capitals."
Ms Harney said that in recent days an analysis of the clients of Citigroup, one of the world's largest banks, had said that a No vote would be damaging for the applicant countries.
"It would begin to cost them millions from the very day after our referendum. Not later, not theoretically, but right away and in real money terms. Their cost of borrowing would increase, as investors would see the delay in their joining the EU as making their government bonds less attractive. The analysts for Citigroup pointed out that applicant countries would be delayed from joining the EU at least until 2006-07, instead of 2004." That, she added, was one view from the world outside Ireland.
The argument from No campaigners inside Ireland that a No vote would not delay or stop new member states joining was simply wrong, she said. "It is not accepted by the applicant countries themselves and it is not accepted by observers who make their living out of calling things right in international markets."
Ms Harney said that before Ireland joined the EU it had little enough influence in European or world affairs. "We had no European Commissioner then. There were few if any Irish people working in European institutions. There were no international meetings in Ireland."
During that time, the North had descended into violence and disorder, she added. "Within the country, women were banned from the workplace if they got married. Equal pay for equal work was just a dream. We had no equality legislation. Our environment had no effective legal protection. Our cities and towns were smoggy. It could take two or more years to get a phone, having paid a deposit.
"For decades, motorways had been built in Britain, France, Germany and Italy, but in Ireland we just had a few miles of dual carriageway and a lot of humpback bridges, bad bends and accidental blackspots."
It was a great act of vision for Irish voters in 1973 to reject this "poor and peripheral" destiny for Ireland, said Ms Harney.
