The trend became obvious early at Dublin's RDS on Saturday night, writes Michael O'Regan, Parliamentary Reporter.
The No side had conceded that the referendum was lost by as early as 11 p.m. on Saturday.
Activists on both sides agreed at the RDS count centre that the results from the six Dublin constituencies, where there was electronic voting, indicated a national trend that the treaty would be overwhelmingly endorsed.
Mr Justin Barrett, of the No to Nice Campaign, said: "The treaty has been ratified by threats, lies, an essentially underhand and filthy campaign undertaken by Fianna Fáil largely speaking. It is not a good day for democracy when the Irish people's will is overturned by big money and big lies."
He criticised the electronic voting system: "The Irish people have a right to have their ballots counted and not to be counted as digits as happened here tonight."
Rejecting criticism by the No side, the Minister for the Environment, Mr Cullen, accused them of speaking "nonsense" during the campaign.
"What the Irish people concentrated on was enlargement and the position of Ireland at the heart of Europe, which has given use jobs, prosperity and growth."
He said these economic issues were at the heart of the acceptance of the treaty.
"There was an understanding, too, that there were countries which had come out from under communism and wanted to enter into the democratic world, offering economic and political stability."
The leader of the Green Party, Mr Trevor Sargent, said he believed Mr Barrett should have stepped down from his involvement in the campaign after becoming the centre of controversy.
"That is hindsight. I think the writing was on the wall for the No side when the Government put out a line that our neutrality was protected. This was nonsense, when you look at American planes in Shannon and the fact that we can join NATO in the morning. There was also the nonsensical threat that, somehow, capital was going to flee the country. Essentially, the Government got away with scare tactics."
The Minister of State for Foreign Affairs, Mr Tom Kitt, said that people had recognised there was a sense of urgency about passing the referendum. "There was no fall-back position. A major effort was also put into the campaign. However, there is no sense of triumphalism on the part of the Yes side. Issues have been raised, and we are now, thankfully, the most informed state in Europe relating to the EU."
The Socialist Party TD for Dublin West, Mr Joe Higgins, said that 80 per cent of the newspaper coverage of the referendum campaign had been on the Yes side. "Also scares were put out, particularly about foreign investment, and Ireland being isolated, which had an impact. Despite the result, the issues raised by the No side will continue to be controversial."
His fellow constituency TD Ms Joan Burton, Labour, said there were voters who found some of the posters used by the No side offensive. "There was a degree of overkill in their campaign. There was also concern among voters about the economic consequences if we voted No."
The Sinn Féin TD for Dublin South West, Mr Sean Crowe, watched as the No vote was decisively reversed in his constituency. He put down the turnaround to the "massive resources" available to those advocating acceptance of the treaty. "Everybody from the ICTU to the IFA were on the Yes side. It is disappointing, certainly, because of the consequences of the Yes vote. We accept the verdict of the people. I am happy enough we got the Sinn Féin vote out in my constituency."
The Fine Gael TD for Dublin South Ms Olivia Mitchell said the "soft Yes" voters had assumed, at the last referendum, that it would be passed. "This time these voters came out in increased numbers. The information gap was also closed this time."