The Minister for Arts, Sports and Tourism Martin Cullen has been admitted to hospital for treatment for a chronic back complaint and is expected to remain there for the rest of the week.
Consequently, Mr Cullen did not attend this morning's Cabinet meeting.
Some of his engagements - including a trip to the west coast of the US - are being undertaken by Minister of State Martin Mansergh.
Mr Cullen’s health problems have led to strong speculation that he will step down from the Cabinet, thereby giving Taoiseach Brian Cowen an extra position to award in the coming reshuffle.
It is not known if the minister intends making an early announcement about his intentions.
Elsewhere, A spokesman for the Green Party has said suggestions that John Gormley might step aside as Minister for the Environment in favour of one of his backbenchers as part of a reshuffle are 'speculation'.
TV3 had reported that the move would come as part of an agreement to rotate the party's senior ministry.
A spokesman said tonight that Cabinet appointments were entirely a matter for the Taoiseach who was consulting John Gormley.
He said they were the only two individuals who knew the timing of the impending reshuffle and the personnel changes it would entail.
He said at this stage anything else is just speculation.