The fate of the Lisbon treaty is poised on a knife edge as the latest opinion poll puts the Yes campaign back into a three-point lead.

The Red C poll for the Sunday Business Post — which has never shown a lead for the No vote — shows the gap between the sides continuing to narrow. No campaigners may feel they have the momentum, since the No vote is increasing by a faster rate.

The survey taken early last week shows 42% in favour and 39% against. The Yes camp is up by one point since the last Red C poll two weeks ago, while the No vote has jumped six points. The Don’t Knows have shrunk from 26% to 19%.

But among those certain to vote, the Yes side has a 46 to 37 lead. As the three large Dail parties stepped up their canvassing, No campaigners switched their focus to trade union concerns, to capitalise on the demand by Siptu (the Services, Industrial, Professional and Technical Union) for guaranteed collective-bargaining rights for all workers. Jack O’Connor, Siptu president, said Thursday’s vote was an important decision for the Irish people and for workers in Ireland, and has repeated his union’s refusal to call for a Yes vote without a pledge on recognition. “We would very much like to be able to recommend to our members that they should support the treaty,” he said.

But Siptu would do so only if the government confirmed that entitlement to the benefits of collective bargaining, and the prohibition against discrimination for those seeking to use it, “will actually apply to workers in Ireland”.

Campaigning in Kerry yesterday, taoiseach Brian Cowen repeated his position that collective bargaining for workers could only be dealt with at social partnership talks. He said he would do all he could to ensure the issue is dealt with satisfactorily.

The Referendum Commission is backing a plan by Rock The Vote, a non-partisan campaign group, to use mobile phone technology to encourage more people to go to the polls.

The group is planning to send two text messages to every phone owner in Ireland. on June 12. One, on Thursday morning, will tell people that polling stations have opened, and another in the evening will remind people when they close. Rock The Vote is in talks with mobile phone operators, all of whom have indicated they are prepared to support the idea.

The scheme, to be finalised in the next few days, has been approved by the Data Protection Commissioner.

The Referendum Commission has said that the plan would “fit in perfectly” with its advertising plans. “This initiative could be a positive contribution by the network operators to democratic life in Ireland,” it said.

Gearoid O’Rourke, director of Rock The Vote, said: “We think this will be a useful and reasonably non-intrusive way to reach millions of people and to encourage them to go vote.

“It will be fantastic for the mobile phone companies to do this. The reminder will be non-partisan, and simply remind people that June 12 is polling day.

“It’s vital that people vote and studies have shown that if you use text messages to remind people to vote, it increases turnout by as much as 4%.

This would be a one-off, and if people can’t vote or don’t want to read the messages they can just delete them. It’s worth annoying a small number of people if more are encouraged to vote.”

Traditionally, the turnout in European referendums has been disappointingly low.

For the first Nice treaty vote in 2001, the turnout was 35%. After a more intensive goverment campaign, it rose to 50% in the second Nice referendum a year later. Turnout in general elections is always much higher and in 2007 was 67%.

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