The confidence and supply agreement between Fianna Fáil and Fine Gael is the linchpin of the current governmental arrangement. It effectively gives Fianna Fáil the power to cause a general election if and how it chooses.
The agreement commits Fianna Fáil to abstain on motions of confidence and budgetary votes. It would collapse if Micheál Martin backed or tabled a motion no confidence in the Government or ministers or refused to allow money bills pass through the Oireachtas.
The deal has been tested on a number of occasions in the 13 months it has been in existence, leading to claims of a possible general election on an array of issues. The most prominent of these incidents were:
Water charges
The issue of water charges was allocated a significant portion of the confidence and supply deal but the issue came to a head in April. At one stage, Fianna Fáil housing spokesman Barry Cowen said the party may not facilitate the election of a new Taoiseach if the dispute was not resolved, which would have breached the agreement.
The water charges issue has not been fully settled, however, with legislation to give effect to the deal reached between Fianna Fáil and Fine Gael expected in the coming weeks.
Maurice McCabe controversy
At the height of the controversy over Garda whistleblower Maurice McCabe in February, Fianna Fáil justice spokesman Jim O'Callaghan said the Government could collapse over disputed accounts of a meeting between him and Tánaiste Frances Fitzgerald, who was then minister for justice.
Appointment of Máire Whelan to the Court of the Appeal
The most recent example of Fianna Fáil expressing concern about the confidence and supply deal came over the past week. Mr O'Callaghan said the appointment of the former Attorney General to the Court of Appeal would amount to a "breach" of the deal, specifically the clause which says there should be no surprises.
The deal says the Fine Gael led minority Government agrees to "have an open approach to avoiding policy surprises". Taoiseach Leo Varadkar said this did not extend to appointments made by the Government.
Confidence in Garda Commissioner Noirín O'Sullivan
Although not a dispute based on the confidence and supply deal, Ms O'Sullivan's position and the ongoing controversies around An Garda Síochána have also seen brinksmanship between Fianna Fáil and the Government.
Mr Martin, Mr O’Callaghan and other party TDs have said they have no confidence in Ms O’Sullivan but say they will not back a Dáil motion to that effect. Mr Martin says it would set a dangerous precedent whereby public servants could be removed from office by a vote in the Dáil.