Fine Gael leader Enda Kenny today insisted a FG-lead government was still possible and tried to derail Bertie Ahern's efforts to form a coalition.
As talks continued between Fianna Fail and the Greens over the formation of a new administration, Mr Kenny warned potential coalition partners to first seek assurances over Mr Ahern's private finances.
The general election results put Mr Ahern in the driving seat to form a new government, but Mr Kenny insisted fresh Mahon tribunal allegations undermined the stability of a Fianna Fail-led administration.
The Fine Gael leader said: "On the Friday night of the count in the election I made the point that an alternative government was possible and that is still possible if the parties that can form that government are of a like mind to do so.
"I made the point that any party now going into government with Mr Ahern is a party to instability.
"I would remind you that the big issue that was raised about stability during the campaign was raised by the fact that two parties sought clarifying statements from Mr Ahern.
"That statement was accepted at face value but the Mahon Tribunal statement of the May 28th contradicts the evidence in that statement.
"And it is a matter for the parties that want to support Mr Ahern in government to resolve that or face instability."
Fianna Fail and Green Party delegations are today holding talks on forming a future government. Mr Ahern is examining the possibility of forming a coalition with a comfortable majority made up of Fianna Fail, the PDs, the Green Party and a number of independents.
Fine Gael and Labour trail Fianna Fail by seven seats but Mr Kenny today hung on to the remote, if mathematically possible, prospect of forming a new government.
"The Green Party have made it perfectly clear they are willing and available to talk to anybody in respect of an alternative government," he said.
"And I make the point very clearly that in discussions that are taking place between the Green Party and Fianna Fail, which is their right, they do need to resolve the matter of the inherent instability arising from the new issues that have been raised following Mr Ahern's own statement which has been contradicted by the Mahon Tribunal statement of the 28th of May."
Mr Ahern has denied any wrong-doing despite concerns raised over his private financial dealings and has said he is co-operating fully with the Mahon tribunal.