Tributes were paid to Ms Joan FitzGerald from across Ireland and Britain, when her death was announced yesterday.
The wife of the former Taoiseach, Dr Garret FitzGerald, died peacefully at their home in Dublin on Saturday night. She had been ill for some time.
The Taoiseach, Mr Ahern, said he learned "with profound sadness" of her passing.
"Joan FitzGerald made a significant impression on Irish political life, particularly during her husband's two terms as Taoiseach."
Mr John Bruton, leader of Fine Gael, said Mrs FitzGerald had had "an acute political intelligence and great personal courage" and he extended his "deepest sympathy to her grieving family".
Mr John Hume, leader of the SDLP and MP for Foyle, described her as an "outstanding person. I knew her well," he said. "She made a great contribution and was a very strong figure during Garret's historic time as Taoiseach."
The Fine Gael Party chairman, Mr Phil Hogan, said she was "an excellent lady who was a great support to Garret. They were probably the happiest couple In Ireland."
The deputy leader of Fine Gael, Mrs Nora Owen, said she was "an inspiration in dealing with her illness . . . a constant source of good advice".
Mr Alan Dukes TD, a former leader of Fine Gael, described her as a "support and inspiration to Garret".
Mr Ruairi Quinn, leader of the Labour Party, said it was with great sadness that he heard of her death. "She was a warm-hearted woman who will be deeply missed by her family and friends."
Ms Gemma Hussey, a member of Garret FitzGerald's government from 1982 to 1987, referred to Mrs FitzGerald's "determination to help strengthen candidates for the party when Fine Gael was trying to make a big breakthrough.
"I remember her arriving, physically disabled as she was, for a coffee morning in Bray on my behalf when she spoke tirelessly to hundreds of people . . . this effort was repeated throughout the country," she said. Mr Noel Dorr, Irish ambassador in London from 1983 to 1987, described her "emotional commitment" and "good sense approach to politics". He spoke of "Garret's unassuming devotion" to her.
"I remember some time in the 1980s Garret was being awarded an honorary degree by the University of Keele, and we all got the train. Garret wheeled her wheelchair into the hall. Always, even when he was Taoiseach and there were lots of people around to help, he looked after Joan. There was no big deal about it, no question."
Sir David Goodall, one of the chief negotiators on the British side of the 1985 Anglo-Irish Agreement, said: "She had a tremendous spirit and a wicked wit, which helped her overcome her infirmity," he said from his home in York. "She was obviously a person of enormous strength. She also had a great ability to look beyond politics, to the bigger picture, which is what I think made her such a tremendous support to Garret."
He tells of a private dinner he had with Joan and Garret outside Dublin just after the Anglo-Irish Agreement had been signed. "I was wearing a ready-made black bow tie, which I though was rather beautiful. But she spotted it immediately and wouldn't let me forget it. She said a gentleman should never wear a made-up tie."
Mrs FitzGerald is survived by her husband Garret, her daughter Mary and her sons John and Mark. Removal will be to the Sacred Heart Church in Donnybrook at 6 p.m. this evening, followed by funeral Mass at 10 a.m. tomorrow.
