By Shane Harrison BBC Dublin correspondent

The Irish Prime Minister, Bertie Ahern, is today a relieved man.

It's a very important vote for Ireland, for Europe but mainly for the applicant countries

Bertie Ahern, Irish Prime Minister

Shortly after his coalition government was returned in May's general election he said getting the Nice treaty passed would be his priority so that 10 applicant states could join the EU as planned in 2004.

He delivered. But the campaign was not without its anxious moment.

Mr Ahern is not as popular as he once was with his government battling allegations that he bought the election win by not telling voters the truth about the poor state of the public finances.

'Good Europeans'

Mr Ahern knows that his popularity has not suddenly returned but he can take comfort in the fact that the disgruntled voters decided not to punish him on Nice.

Yes campaigners argued enlargement would boost the economy

Instead, they decided to once again become "good Europeans". As Mr Ahern said, Ireland is now back at the heart of Europe.

"It's a very important vote for Ireland, for Europe but mainly for the applicant countries," he said.

"They have worked for 10 hard years. It means an enormous amount to them. And I think Ireland will be seen in a good light right across eastern and central Europe today."

Neutrality threats dispelled

So, why was the first Irish referendum on Nice defeated 17 months ago? And why a second referendum?

The Irish result was a good news for Polish Prime Minister Leszek Miller

The Nice treaty gives the current EU states until the end of this year to adopt the treaty that proposes a number of changes to the way it makes its decisions before enlargement.

Once the treaty was rejected in May 200, the Irish Government knew it had time to reverse the NO vote even though anti-Nice activists accused it of ignoring the democratic will of the people.

Research showed that voters last time had great concerns about perceived threats in Nice to Irish neutrality.

So, the government sought and got a declaration from the other members states at Seville earlier this year saying there was nothing in the treaty to compel Ireland to sign up to a mutual defence pact.

Vigorous campaigning

The government was also very aware that last year it took the people for granted, did not campaign as hard as it might have and just assumed that voters would endorse another European treaty because they had always done so in the past.

This time nothing was left to chance.

Bertie Ahern campaigned vigorously knowing that his very survival as prime minister might depend on the result.

Polling day was moved to Saturday to encourage more people to vote because only 35% bothered to do so last year when the NO side got 54%.

Voters were continuously told Nice was about EU enlargement and nothing else.

It worked. Turnout this year was 48%, and 63% voted YES.

It's been a good day for Bertie. He may not yet have recovered his Teflon coating or his lost popularity but as he himself would say: "Sure, it's a start."