The British Prime Minister, Mr Blair, is to visit Northern Ireland again this week as part of a concentrated effort to reverse the trend of unionist opinion and ensure a strong Yes vote in Friday's referendum.
And in an attempt to attract young voters, the Ulster Unionist leader, Mr David Trimble, and the SDLP leader, Mr John Hume, are to make a unique joint appearance on the stage at a rock concert in Belfast starring U2 and the prominent Northern band, Ash, tomorrow night.
The idea for the concert, which will also be televised, is reported to have come from Bono, lead singer of U2. Last week's Irish Times/MRBI opinion poll showed that the highest percentage of undecided voters was in the 18-24 age group.
The Taoiseach, Mr Ahern, yesterday pledged that the Government would pursue the implementation of the agreement's provisions on decommissioning.
Approval of the agreement "will represent an unassailable democratic verdict" Mr Ahern said, in a statement, adding that any subsequent violence "will be firmly crushed". Mr Trimble is fighting for his political life: at a news conference in Derry today, he will be joined by the leader of the Conservatives in the House of Lords, Viscount Cranborne, and the Antrim-born Labour MP, Ms Kate Hoey, in an appeal for a Yes vote.
Meanwhile, the UK Unionist Party leader and prominent No campaigner, Mr Robert McCartney, has challenged Mr Blair to a debate on the Belfast Agreement.
He said the Prime Minister could not introduce legislation to bar Sinn Fein from a Northern Ireland administration because this would be inconsistent with the terms of the agreement, which only required parties to use such influence as they may possess for the purpose of achieving decommissioning.
The terms and conditions of a multi-party agreement could not be amended unilaterally by one of the parties. This principle had been confirmed by the House of Lords, Mr McCartney said.
In an effort to counteract Mr McCartney's arguments and his prestige as a lawyer, the UUP is making its party headquarters available this morning to a group of senior barristers who favour a Yes vote.
The battle is now focusing on a small percentage of voters. Observers believe that if the Yes vote is less than 65 per cent, Mr Trimble's position will be extremely difficult and the prospect of making the Northern assembly and the North-South bodies work unlikely.
Informed observers believe the likely outcome, unless the trend can be reversed in the next few days, is a Yes vote just above 60 per cent, with a lower percentage not entirely ruled out. "Blair's going to make a real effort again," sources close to British government thinking said.
There was a boost for Mr Trimble from the Sunday Telegraph which yesterday urged a Yes vote. An editorial in the paper said a No vote "would almost certainly not improve the lot of the Unionist majority".
The Yes campaign still believes Mr Blair is its best asset and hopes that by repeating his assurances on decommissioning, prisoners and other issues, he can steady unionist opinion, save the agreement, and avert his first major political disaster since taking office.
Arrangements for the Blair visit have not been finalised but there is speculation it will take place on Wednesday. "People still respect the Prime Minister as the ultimate source of authority," one leading Yes campaigner said.
It is understood, however, that the indications in private surveys carried out for the British government continue to be a source of concern to the Yes campaign.
The SDLP has deliberately kept a low profile during the referendum campaign because it would not have helped Mr Trimble to have high-profile nationalists extolling the merits of the agreement.
"We're aware of the difficulties others are facing," senior SDLP sources said. However, the party is planning a major campaign rally in a Belfast hotel on Wednesday night.
An opinion poll in today's Daily Telegraph shows a continuing high proportion of undecided voters at 21 per cent, with support for a Yes vote at 61 per cent and 16 per cent opposed to the agreement.
The RUC carried out a controlled explosion yesterday on a suspect vehicle left outside the police station in Newry Road, Armagh. Republicans opposed to the peace process were blamed for planting the bomb but no specific group was identified.