The President has already declined an invitation to today's service.
A controversial religious event marking the centenary of Northern Ireland takes place in Armagh this morning.
President Michael D Higgins declined an invitation to the service, saying the title was not politically neutral.
But Foreign Affairs Minister Simon Coveney and Government Chief Whip Jack Chambers will attend.
Aontú leader and Meath-West TD Peadar Tóibín thinks they should have refused to go:
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