Tánaiste Michael McDowell's description of the Taoiseach's acceptance of €50,000 from his friends in the 90s as an "error of judgement" has been described as a "self-serving" attempt to prop up the Government.
Mr McDowell, who is also Minister for Justice, broke the Progressive Democrats' virtual silence on the issue this evening after a meeting of the parliamentary party.
He said the money given was "well-intentioned" and not intended to gain political favour but that Mr Ahern had made an "honest error of judgement" in accepting it.
Mr Ahern has said he accepted the money from friends in 1993 and 1994 as a loan to help pay for costs associated with his marital separation, however he had not repaid it.
Green Party chairman John Gormley said the Tánaiste's statement was "a serious cop-out" and an "insult" to voters who elected the Progressive Democrats to monitor for Fianna Fáil in government.
Mr Gormley recalled the PD election slogan "single party government - no thanks" and said it had come back to haunt Mr McDowell.
"Clearly, he has decided to put political ambition ahead of principle by continuing in Government," he said.
Labour Party leader Pat Rabbitte picked up the theme saying Mr McDowell's assessment was "self serving formula worked out to keep the PDs in office".
"We may as well have single party government, as the PDs are now handcuffed to Fianna Fáil for the duration of this Dáil.
"After almost a week of untypical silence, Mr McDowell has made a fateful decision for himself and his party," Mr Rabbitte said.