INDEPENDENT TD Tony Gregory, who died yesterday, was an insightful politician who served both his city and country well, Taoiseach Brian Cowen said.
Leading the tributes, Mr Cowen said he was saddened to learn of the "untimely passing" of a "proud Dubliner, a great advocate for his community and a diligent public representative".
"Tony was always courteous and had a fine sense of humour. He had an insightful knowledge of many issues, especially social deprivation and the problems caused by drugs," Mr Cowen said. "The people of Dublin Central consistently voted for Tony because of his well-deserved reputation for hard work and his commitment to the disadvantaged in our society."
Former taoiseach Bertie Ahern, a strong rival for decades of Mr Gregory, said they had been "constituency colleagues, political opponents and always good friends" for 30 years.
"I want to pay tribute to a politician who gave total commitment to his constituents and made an undoubted difference to the city he loved. Though Tony and I come from different political traditions, we both shared a deep commitment to our constituents and a desire to help the less well-off in our society. I have always readily acknowledged that."
Offering sympathies to Mr Gregory's brother, Noel, and all those close to him, Mr Ahern said he had never "sat on the sidelines" but had always tried to improve the lives of his fellows.
Fine Gael leader Enda Kenny described Mr Gregory as "a fearless defender" of his constituents, "proud of his heritage and absolutely courageous in standing up to drug barons and drug pushers.
"He epitomised his love of country by his continuous and frequent use of the Irish language, which he spoke so well and with such clarity. He bore his illness with great dignity.
"Typical of his demeanour and personality, he said in reply to my asking how he was, just some short time ago: 'I don't talk about it, this is something I have to cope with myself, alone.' I admired his conviction and his total commitment to his people. We shall miss him," Mr Kenny said.
Socialist Party leader Joe Higgins said Mr Gregory's electoral success over nearly three decades was a "testament" to his resilience and the willingness of working people to elect "fighters".
"It is a paradox - but one that stems from that decision [to support Charles Haughey] in 1982 - that more emphasis will be put on the short-lived Gregory Deal than on most other aspects of his political life when, in fact, Tony Gregory detested the right-wing policies of the establishment parties, including those of Fianna Fáil."
Independent TD Finian McGrath said he would not have reached Dáil Éireann except for Mr Gregory's "support and guidance" over 25 years.
"Ireland has lost a great TD and a champion of the weakest sections of society," Mr McGrath said. "He taught me everything about politics. Above all he was a man of great ability and integrity."
Green Party leader John Gormley said: "He was a strong feature of Irish political life since 1982 and his passing came all too early for someone who still had much to give."
Senator Paschal Donohoe, also Dublin Central, said it was an honour to work in the same constituency as Mr Gregory. "He was a servant of the people and worked tirelessly for them and for the community," he said.
Labour councillor Aodhán Ó Ríordáin said Mr Gregory had been "a hero of the people" at a time when few politicians stood up for those living in neglected districts.
President Mary McAleese has conveyed her sympathies to Mr Gregory's family.