Fianna Fáil Senator Kieran Phelan has died suddenly in Dublin.
Senator Phelan, who was 60, fell ill at his hotel this morning, shortly before the Seanad met.
He is survived by his wife, Mary, and five children.
A farmer and auctioneer from Raheen Upper, Donaghmore, Portlaoise, Co Laois, he was first elected to the Seanad in 2002.
He was re-elected in 2007 and sat on the Industrial and Commercial Panel.
He was a former member of Laois County Council and was elected chairman of the Council in 1998.
Taoiseach Brian Cowen has paid tribute to Senator Phelan.
Mr Cowen said Senator Phelan had been a well-known and respected member of the Seanad, as well as being his constituency colleague and life-long friend.
The Taoiseach extended his sympathy to the late Senator's immediate and extended family.
The Seanad also paid tribute to Senator Phelan. Leader of the House Senator Donie Cassidy has proposed that the House be adjourned until 1 June because of the death.
Fine Gael Seanad leader Frances Fitzgerald said: 'It was with a real sense of shock and sadness that I heard of the sudden passing of our colleague, Senator Kieran Phelan, this morning.
'My heartfelt sympathy goes out to [his family] on this extremely sad day at this most unexpected time.'