Two Labor MPs have been sent to the High Court over their citizenship status but the Turnbull government's plan to unilaterally refer three others has been blocked, giving Bill Shorten some reprieve after a horror fortnight that has left many in his team dismayed.
ALP senator Katy Gallagher's case will now serve as a test case that will determine the future of backbenchers Justine Keay, Susan Lamb and Josh Wilson. If Senator Gallagher is disqualified, the trio of lower house MPs will likely be forced to resign - sparking three byelections in 2018.
Labor is already bracing for a tough byelection, after agreeing to refer Victorian MP David Feeney to the court because he could not produce proof he renounced his British citizenship. Party hardheads are weighing whether to dump Mr Feeney as candidate in a bid to fend off the Greens.
Leader of the House Christopher Pyne said it is still the government's view that the other MPs should be referred to the High Court but he conceded the Coalition was unlikely to get the numbers to make it happen, after the crossbench sided with Labor.
"The High Court will rule on the status of Katy Gallagher," Mr Pyne said. "If Katy Gallagher is disqualified those three members should resign, the same way that Barnaby Joyce resigned after he went to the High Court and was found to be ineligible."
Labor sought on Wednesday to refer all its doubtful MPs along with four Coalition members: Liberals Jason Falinski, Alex Hawke, Nola Marino and Julia Banks.
But the government is refusing to countenance any further referrals from its own side, and the casting vote of Speaker Tony Smith defeated the Labor motion. While questions have been raised about gaps in their documents, the government says its MPs are all in the clear.
Labor's gambit ground Parliament to a halt and forced a delay in the debate about same-sex marriage.
Labor's counterattack was also blunted when its pursuit of Energy Minister Josh Frydenberg over his possible dual citizenship began to split the party. Labor MPs Michael Danby and Ed Husic publicly criticised the decision to target him, given his parents arrived in Australia stateless after escaping the Nazis.
Labor MPs are dismayed by how the final week of the parliamentary year has played out, with many criticising the Opposition Leader and his office for their handling of the citizenship crisis.
The revelation about David Feeney's citizenship issues had been, as one MP put it, a "total curveball" that had rocked Labor back on its heels.
A senior MP said Labor's approach to the citizenship fiasco in recent months had been "all about tactics and winning the day and not about the long game".
"This has blown up in our faces, there are a lot of people concerned about how this has been handled."
Multiple MPs said the series of stories about Sam Dastyari's links to Chinese Communist Party-linked political donor Huang Xiangmo had damaged the opposition, in a week during which there had been public speculation about Malcolm Turnbull's hold on the job as Prime Minister.
Senator Gallagher is in an identical position to Ms Keay, Ms Lamb and Mr Wilson: she took steps to renounce her foreign ties but did not have it officially confirmed before nominating as a candidate at last year's election.
Labor argues all will be protected because they satisfy the "reasonable steps" test but the opposition could be forced to defend itself in four lower house byelections, with Mr Feeney's case more problematic.
He approached Mr Shorten early last week to tell him he could not locate any renunciation documents and he was seeking further advice.
Mr Shorten told Mr Feeney - a key Victorian ally and friend who was best man at the Labor leader's wedding - that he had until the December 5 deadline to produce the proof or he would face possible High Court referral. The Opposition Leader is said to be "absolutely furious" with the MP.
In a sign of how just how angry Labor figures are with Mr Feeney, discussions have begun about dumping him from Batman and standing another candidate if the High Court orders a byelection. Labor strategists in Victoria believe he would most likely lose his seat to the Greens if he stands.
Mr Turnbull dismissed Mr Feeney's claims to have lost his documents, saying he should resign immediately, just like Liberal MP John Alexander.
"He lost his papers. Did the dog eat them? Did he leave it in the house he overlooked? If you can overlook a house, you can presumably overlook a few papers?" Mr Turnbull said, referring to the $2.3 million home Mr Feeney failed to declare last year.
Mr Falinski produced new legal advice from law firm Arnold Bloch Leibler that concluded he was not a citizen of Britain, Poland, Russia or Kyrgyzstan - but noted "we cannot conclusively advise on foreign law and recommend you seek independent advice".
While Ms Marino presented evidence on Wednesday she was not an Italian citizen through her marriage, Labor immediately sought to raise doubts about whether she could have inherited US citizenship from her father.
In the case of Mr Hawke and Ms Banks, Labor maintains registration of their Greek citizenship is simply an administrative step necessary to obtain a passport and not a necessary step to become a Greek citizen.
Tensions also boiled over between Labor MPs and the media, when backbench MP Brian Mitchell was caught on camera calling an ABC reporter a "maggot" for questioning Ms Keay about her status. Mr Mitchell later apologised.