Explainer: A very rough Day for Malcolm Turnbull's agenda
ANY hope of the Turnbull Government prosecuting its own agenda could be thrown out the window as the resignation of Family First Senator Bob Day raises questions of whether he should have even been there in the first place.
As set out in the Constitution, the Commonwealth is not allowed to have a "direct or direct pecuniary (financial) interest" with any politician.
Where that occurs, the person involved in the deal would be disallowed from standing for Parliament.
Enter Mr Day, who was working in an office paid for by the Parliament, but which was owned by a company with links to Mr Day.
The Commonwealth has not paid rent for the office space, but has a lease with the building's owners.
When he was elected, the ABC reports Mr Day sold the premises to associates, but backed the loan they used to buy it.
By supporting that loan, it may have created a breach of the constitution.
This means that in light of his resignation, all South Australian Senate votes need to be recounted from the July 2 election.
Depending on the outcome, it could mean Family First loses its Senate seat, and is replaced by an Labor or minor party Senator -- which would narrow the already tiny sliver of support the Government enjoys in the Upper House.
Attorney-General George Brandis has now referred the issue to the High Court, which considers such matters as the Court of Disputed Returns.
The wording of the constitution is not precise, and has never been tested by the courts.
When this happens, it could set a new precedent that decides who is allowed to enter the Parliament, and could have consequences for those already elected.
Family First has denied any knowledge of a conflict, and Mr Day has denied one exists.
The party is seeking its own legal advice, no doubt hopeful that it can hold on to the key seat in the Senate.
If Family First loses the seat, there's no clear way of knowing who would replace it given the complicated preference deals that have been done.
ABC election expert Antony Green did modelling of his own which suggests Labor's Anne McEwen would likely pick up the seat if the court rules against Family First.
For the Federal Government, this rough day could be about to get rougher.