The result of Ireland's Lisbon Treaty referendum will have implications for the wider European Union.

Ireland is the only one of the 27 member states holding a referendum - meaning a country accounting for less than 1 per cent of the bloc's 490 million population could derail a pact designed to reform how it is run.

A survey last week put opponents of the Treaty, which replaces a constitution rejected by French and Dutch voters in 2005, ahead for the first time.

Rejection at the polls will influence the ratification processes of other countries and effectively kill the Treaty dead.

An international referendums expert said Ireland was unlikely to be offered a second referendum as it was when the first Nice Treaty was rejected in 2001 but approved a year later.

"The legal position is that if one country rejects the Treaty, then it falls," said Professor Matt Qvortrup of Scotland's Robert Gordon University.

"A no verdict in Ireland will also adversely affect the current ratification process of a number of other EU states like Britain, the Czech Republic, Poland and Denmark."

Prof Qvortrup, who has authored three books on referendums held in Europe, the US and Australia, said it was unclear who would take the blame if the Treaty collapsed.

"As individual member state governments negotiated the terms, heads are unlikely to roll in the EU Commission," he added.

Opponents say the treaty will allow the EU to force Ireland to raise low corporation taxes, which have drawn investors to Ireland and encouraged companies such as Google and Yahoo! to set up their European headquarters in Dublin.

Most parliamentary parties, business, the congress of trade unions and a powerful farming lobby have campaigned for a "Yes" vote, but they acknowledge the complex treaty text has made it difficult to convince voters.

If Irish voters return a yes vote, then the terms of the Treaty will begin to be implemented across the member states.

Ireland and its EU neighbours will immediately enter into the rotation process to nominate a Commissioner for two out of every three five-year terms.

A permanent EU president with a 36-month term will be recruited, as will a Foreign Minister.

The way will also be cleared for the roll-out of other new provisions on tax, voting powers, military policy and opt-out mechanisms.

On Wednesday, the House of Lords rejected a bid to force a UK referendum on the Treaty.

Liberal Democrats sided with the Government to defeat the Conservative move by 280 votes to 218 - a majority of 62.

The vote clears the way for Parliament to ratify the treaty.

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