Taoiseach Brian Cowen denied today giving a live radio interview while drunk or hungover.
Mr Cowen was challenged over his handling of an RTE morning broadcast from his Fianna Fail party's annual get together ahead of the new Dail term.
The opposition claimed the interview came on the back of a late night and prompted concerns over Mr Cowen's ability to lead the country.
Questioned on his way into the second day of parliamentary party meetings in Galway, the Taoiseach denied alcohol was a factor in the heavily criticised performance.
"I'm sorry, absolutely not. I mean, that's ridiculous," the Taoiseach said.
"It's not true at all, please."
Mr Cowen said the nine minute interview, live on RTE's Morning Ireland shortly before 9am, was a "good conversation".
He also hit out at being questioned over his fitness to go on-air, saying: "Really, that's uncalled-for."
Mr Cowen, who attended the Fianna Fail party dinner last night, was beginning day two of his party's annual pre-Dail meeting at the Ardilaun Hotel in Galway city when he faced a barrage of criticism online and on air.
There has been ongoing criticism over Mr Cowen's ability to communicate with the public in interviews during his time in office.
Michael Noonan, Fine Gael's finance spokesman, led the criticism but insisted he was not making a personal attack on the Taoiseach or political point-scoring.
"I was listening to the interview. He certainly was a man who was coming at the interview at the end of a very late night," Mr Noonan said.
"He was uninspiring. He certainly didn't sound like man who was going to lead the country out of the problems it's now in."
The opposition spokesman also said late nights are part of professional politics.