The Government's decision to hold the second Nice Treaty referendum on Saturday, October 19th, was designed to maximise the youth vote, the Taoiseach, Mr Ahern, has said.
Speaking after the Cabinet's meeting in Glenveagh National Park, Co Donegal, Mr Ahern repeatedly emphasised that voters must decide whether or not they wished to slow the pace of European Union enlargement.
Polling stations will be open on the day from 9 a.m. to 9 p.m. for the 2,923,918 registered voters, although applications from people wishing to be added to the supplementary voting register will be accepted until October 4th.
Seeking to simplify the issue, the Taoiseach said: "You can get tied up in complexities, but this is all about enlargement: to allow Central and Eastern Europeans to join their fellow Europeans after a decade of working hard and a half-century of Soviet rule."
He criticised as "highly irresponsible" the call made yesterday by the Tipperary South Independent TD, Mr Séamus Healy, who urged voters to use the referendum to punish the Government for its mid-year budgetary changes.
"I would say to Séamus Healy: he obviously doesn't take his national responsibilities much into account, and it is a pity that a public representative takes that view," the Taoiseach told The Irish Times.
The European Union was on the verge of expanding to include 500 million people, he went on. "The decision facing us is whether we want to be part of that, or do we not; or, even worse still, do we want to block it - even though we would ultimately fail."
News that the Taoiseach had opted for a Saturday became clear to most of his Cabinet colleagues only after the two-hour Glenveagh meeting began. On Wednesday evening, Mr Ahern had said that some "tidying up" still had to be done before a date could be set.
The decision to opt for a Saturday was agreed after discussions between Mr Ahern - who has never displayed much enthusiasm for weekend voting up to now - and the Minister for the Environment, Mr Cullen.
Weekend polling will help third-level students who return home at weekends to vote, along with workers such as sales representatives, said Mr Ahern. "Obviously, we will lose those who go away for the weekend," he added.
The Government is meeting the minimum 30-day period required by the Constitution, although the Taoiseach was at pains to dismiss suggestions that this will be a "short" campaign. "Thirty days is a long campaign," he said.
October's political calendar is complicated by the fact that a meeting of the European Council will take place in Brussels on October 24th/25th, while the 15 EU leaders will meets days later with representatives of the candidate countries in Copenhagen.
Up to now, Saturday polling has taken place only in Udarás na Gaeltachta elections and by-elections and opinion is divided on whether it did much to increase voter turnout.
Speaking after the Cabinet meeting ended, the Tánaiste, Ms Harney, said: "A Saturday will allow the maximum number of people to vote. A high turnout is important, because ratification is essential for Ireland."
Rejecting criticism from the former leader of Fine Gael, Mr John Bruton, that the Government had delayed setting a date, Ms Harney said that it done so as quickly as possible.
The Cabinet meeting in Glenveagh National Park - the first to be held in Co Donegal - was also the first to be held since the referendum legislation had passed through the Oireachtas, she said.
The "full weight" of the Cabinet, the Fianna Fáil Parliamentary Party and Fianna Fáil's national organisation would now be thrown behind the campaign for a Yes vote, said the Minister for Social Affairs, Ms Coughlan.
The Minister for Rural and Community Affairs, Mr Ó Cuív, who voted No last time, said he believed "a lot of fears" had been assuaged by the Government over the past year, particularly on neutrality. He also cited the Government's promise to assist the Oireachtas in rigorously examining EU legislation.