Fine Gael has warned Fianna Fáil that it must fully cost any proposals it intends to raise as part of the review of the Confidence and Supply Agreement.
This is the arrangement between the parties that keeps the Government in place.
The warning comes just two days before the parties are set to sit down to begin reviewing of the agreement.
These talks will ultimately determine whether or not there will be a General Election or if the Government will remain in office for another budget.
There are expected to last for several weeks.
A spokesperson for the Taoiseach said this evening that good financial discipline should be a key component of the discussions.
"Everything should be costed and well thought out," the spokesperson said.
They pointed out that it's now 52 days since the Taoiseach wrote to the Fianna Fáil leader requesting that these talks begin.
Meanwhile, Taoiseach Leo Varadkar has accused Fianna Fáil leader Micheál Martin of being "obsessed with innuendo and conspiracy theories" during tetchy exchanges in the Dáil chamber.
On the week that talks on renewing the Confidence and Supply deal are due to commence, Mr Martin asked the Taoiseach for details of the Government's investigation into the leaking of some of the Scally Report into the CervicalCheck scandal.
Mr Varadkar said it was "disgusting" that the report was leaked, but Mr Martin accused the Taoiseach of being "breathtakingly cynical".
Mr Martin said: "You know and I know that media protects its sources. It's a bit much to suggest now that given the propensity of Government ministers to leak to various political correspondents and people across the board on a regular basis, that you are allegedly sincere in your attempt to get them to cough up the source. I think that is breathtakingly cynical."
The Taoiseach responded to Mr Martin by saying "he has quite a history in the last couple of years of engaging in innuendo and making allegations against people that in some cases turn out to be false".
WATCH: @campaignforleo claims @MichealMartinTD is "obsessed with innuendo and conspiracy theories" in tetchy Dáil exchange https://t.co/X3DQmHQBGS pic.twitter.com/zG0KhAzBYw
— Conor McMorrow (@ConorMcMorrow) October 23, 2018
Mr Varadkar added: "If Deputy Martin has any evidence that any particular individual or any politician or any advisor or any civil servant or anyone associated with Dr Scally or his team put this information in the public domain by talking to journalists, I would ask him to present that evidence.
"And if he has no evidence, he shouldn't make the assumption that it must have been a politician or a member of Government because he has no basis for that."
The Taoiseach continued: "It should be basic decent politics in this house that we don't make allegations against each other when we have no basis or no evidence for doing so. When it comes to leaks, I often wonder when a leak happens, who did it? Because you presume somebody who did somehow had a plan or thought they would benefit from it in some way.
"In relation to the aspect of the report that was leaked, it was Dr Scally's opinion that a Commission of Inquiry was not necessary."
"Bear in mind, we had made a Government decision already to establish a Commission of Inquiry and the Government still has no difficulty in establishing one. So even the innuendo doesn't make sense on this occasion," said Mr Varadkar.
Deputy Martin pressed the Taoiseach about who is leading the investigation into the leaking of Dr Scally's report.
Mr Varadkar said it was a "disgusting thing to do" to leak the report.
He said the Secretary General of the Government is leading the investigation.
Then he attacked Mr Martin: "Deputy Martin has a really long history of making false allegations against people, or pursuing innuendo and conspiracy theories. His constant charge against me relates to spin because he has no case against us when it comes to substance. My charge against him is that he is obsessed with innuedo and conspiracy theories."
Additional reporting by Conor McMorrow
