Taoiseach Bertie Ahern and British prime minister Tony Blair will give brief addresses at a reception in Stormont on May 8th, after the ministers in the powersharing executive have taken their pledges of office.
The reception will be hosted by newly elected first minister Ian Paisley and deputy first minister Martin McGuinness. The attendance will include some US politicians who have assisted the peace process.
There is speculation that Senator Edward Kennedy, former senator and Stormont talks chairman George Mitchell, and former president Bill Clinton might be present.
A number of US presidential envoys are likely to be present and there are suggestions that secretary of state Condoleezza Rice may attend. Demand for the 150 places at the reception is described as intense.
Meanwhile, European Commission president José Manuel Barroso will visit Belfast next Tuesday for talks with Dr Paisley and Mr McGuinness.