CANBERRA -- Proving there's no quick resolution the citizenship saga in sight, the Federal Parliament is now under constant threat from disruption and other stunts -- including another notable intervention from Tony Abbott.
On Monday, the Opposition failed to rule out disrupting Parliament -- through a dramatic walk-out strategy -- while the most senior pollie in doubt, Deputy Prime Minister Barnaby Joyce, steps in as acting Prime Minister later this week while Malcolm Turnbull is overseas.
Labor will not abide Joyce holding ministerial responsibilities while the High Court considers his citizenship, but the manager of opposition business Tony Burke has distanced himself from the possible tactic.
"We are not going to stop fighting and I think a walk out would be to stop fighting," Burke told the ABC.
But the threat is still in play with deputy Labor Leader Tanya Plibersek admitting "anything could happen".
This, in turn, has set former PM Abbott onto the case, specifically attacking Bill Shorten -- who was born to a British father but hasn't produced paperwork proving he has renounced UK citizenship.
Abbott stood in front of cameras holding up his own British citizenship renunciation letter and called on the Opposition Leader to do the same.
"Bill Shorten claims that he has renounced his British citizenship, but he has never proven it," Abbott told reporters in Canberra.
"I say to Bill Shorten show it or shut up. Show your letter or shut up about Barnaby Joyce because if you haven't got a letter, you are in exactly the same position that he is in.
"What we've got from Mr Shorten is an inability to be straight and I say that he should just be straight with the Australian people about his citizenship. He should show the letter or shut up."
Shorten claims to have renounced his UK citizenship in 2006, but like other Labor members has not provided paperwork.
However, Labor denies it has a citizenship problem, pointing to rigorous checks applied to all of people nominating for election.
"Labor has done nothing wrong," frontbencher Andrew Leigh told Sky News.
"The Coalition has and they've admitted it. Now they want a guy who was admittedly a dual citizen to be the Acting Prime Minister of Australia. That's not a good thing for the administration of the nation."
A short time ago, the Senate formally referred potential breaches of section 44 (i) of the Australian Constitution by Nationals deputy leader Fiona Nash and independent Senator Nick Xenophon to the High Court for determination.
That officially makes them the sixth and seventh cases to be referred to the court, sitting as the court of disputed returns.
Attorney-General George Brandis told the senate that Senator Xenophon's case of possible British dual citizenship proves just how "silly this has become", noting the Prime Minister's view that "if Nick Xenophon is an Englishman, then the Pope is a Methodist".
And One Nation Senator Malcolm Roberts is still to have his case determined by the High Court, Pauline Hanson has called for an audit of all politicians -- citing a public loss of faith and confidence in the Parliament.
Labor and the Coalition did not support the motion from the politician who wore a burqa during Senate Question Time last month and wrote it off as another stunt.