The Labour leader, Mr Dick Spring, has written to each member of his party describing Ms Adi Roche as a "unique and remarkable woman" whom they should elect President on Thursday.
By electing Ms Roche, the country would have a President who had sent more humanitarian aid to Chernobyl than the United Nations, a person who was a director of an organisation that had won the Nobel Peace Prize, a person who was a best-selling author, someone with national standing and "an outstanding international reputation".
"Adi Roche has represented Ireland abroad in the most difficult possible way," Mr Spring says in his letter. "She has brought honour to her country and been honoured herself."
He added that he was especially proud of the way Ms Roche had campaigned despite all the pressures she had been subjected to. "One of the least savoury aspects of this campaign has been the bitter in-fighting between Fianna Fail and Fine Gael," wrote Mr Spring.
The election of the Fianna Fail candidate, Prof Mary McAleese, would send a "strongly conservative message throughout the political system - just as the election of Mary Robinson sent a message of openness and tolerance," wrote Mr Spring.
He urged Labour members to reject the notion of a Fine Gael President and support Ms Roche's idea of "a President of the people".