Writer and former government minister Dr Conor Cruise, O'Brien has sent an open letter to the SDLP leader, Mr John Hume, asking him to make known his support for the repeal or amendment of Articles 2 and 3 of the Constitution.
Dr O'Brien is a UK Unionist candidate in today's election. "Your prestige and authority in the political life of the Republic are such that your support on such a question would be decisive", he wrote.
"No major political party there could oppose such a proposition, once endorsed by you. The parties would move for a referendum and the referendum would carry around 80 per cent."