The Minister for Arts, Sports and Tourism, Martin Cullen, has resigned from government and is also retiring from the Dail (Parliament).
Cullen (56), who hails from County Waterford, has been a Dail member (MP) for 23 years.
Cullen has suffered chronic back problems since an "extremely bad car crash many years ago," in which he broke his neck.
It was expected that he would step down as minister before the cabinet reshuffle that is due to take place after St Patrick's Day.
"I was in hospital for a long time. I consider myself very lucky that I recovered from that and got so many years without the trouble I have faced today. I have chronic back problems and they are getting worse and worse," said Cullen of his decision to step down.
“I have always been a fighter and optimistic in both my personal and political life. However, my consultant’s advice is that my condition is deteriorating further and options for treatment and recovery are narrowing,” he said.
While Cullen's decision to resign from the cabinet was expected, the decision to step away completely was not, and further erodes the government’s majority.
After Cullen’s decision the government holds an 84-78 majority in the Dail.
There are three by-elections due to take place in the coming months, and the government coalition is not expected to win any of them.
Cullen is a former mayor of Waterford and was elected to parliament in 1987 as a member of the Progressive Democrats. He left the PDs in 1994 and joined Fianna Fail.
He was appointed to junior ministry in 1997 and was appointed Minister for the environment in 2002.
Tributes have been paid from fellow politicians.
"While his resignation as a Minister had been widely expected his decision to resign as a TD is a shock and will further erode the stability and life expectancy of the government,” said Labour Party leader Eamon Gilmore.