Fianna Fáil Senator Tony Kett has died after a long illness. He was 57.
Taoiseach Brian Cowen has led tributes to Senator Kett, saying he made a real and lasting contribution to politics.
Former Taoiseach Bertie Ahern said he was deeply saddened at the death of one of his closest friends.
Tony Kett was born in Ballinasloe, Co Galway, in 1951. He was a long-standing member of Fianna Fáil and a key ally of Bertie Ahern in his Dublin Central constituency.
He was co-opted onto Dublin Corporation in 1988, following Mr Ahern's appointment as a Government minister. Mr Kett was first elected to the Seanad in 1997 and was his party's spokesperson on Arts, Sport and Tourism in the upper house.
In a statement the Taoiseach said Senator Kett had demonstrated ability and commitment during his time in public office. Mr Cowen paid particular tribute to his work in the area of disability and educational policy.
Bertie Ahern said he was deeply saddened by death of a man he had enjoyed a close personal friendship with for over three decades.
He said Mr Kett was one of his closest advisors during his time in office and was a loyal and trusted friend.
Senator Kett is survived by his wife Noreen, his son and two daughters.