Two days of discussions with each of the member states ended last night without clear agreement.

Several countries are worried the guarantees in protocol form will lead to a need to re-ratify the Lisbon treaty. Instead they would prefer simple declarations that do not have the same legal weight.

“We have no problems with the content of what the Irish want as long as it is simply restating what is already the situation, as they are. But we are afraid turning them into protocols could lead to demands to reopen the debate on the treaty in our member states,” one diplomat said.

Irish and EU legal experts will spend the weekend putting together the wording for the guarantees and will present them to ambassadors from all EU states at 9am on Tuesday.

However, one diplomat said: “It is very uncertain whether they will be agreed by the ambassadors.” In that event, they would go to the summit on Thursday for decision by the member state leaders, something the Irish wished to avoid.

Every country has said that it wants to help Ireland and would be willing to give the guarantees as declarations. However, this would not necessarily have the same weight as protocols which would become part of the EU legislation when they are appended to the next EU treaty.

The Irish proposed that they would be attached to the next accession treaty, possibly for Croatia. However, the British government has said they will be faced with a demand from the opposition to re-ratify the Lisbon treaty if the new protocols are agreed.

All other 26 countries have ratified it with just the Czechs, Poles and Germans waiting for their presidents to sign it off.

Meanwhile, Fine Gael leader Enda Kenny is worried the Government will not be able to convince the public to vote for the treaty later this year.

He is meeting the Taoiseach next week and has said the campaign must begin immediately.

Asked if the Government could deliver a Yes vote, he said: “That is the question.”