A senior Labor frontbencher has reluctantly thrown a lifeline to his embattled colleague David Feeney should the High Court send him off to a by-election.
Mr Feeney has been referred to the court to clarify his citizenship status, because he could not find documentation relating to the renunciation of his UK citizenship back in 2007.
He is the second Labor MP to be referred to the court, following Senator Katy Gallagher.
Manager of Opposition Business Tony Burke expressed little sympathy for Mr Feeney in an ABC radio interview on Wednesday evening.
"When it came time to actually find the document, one of the documents hasn't turned up. Now, I find that weird," Mr Burke told ABC Radio.
He was asked repeatedly whether the party should endorse Mr Feeney to be Labor's candidate at a potential by-election for the marginal seat of Batman, but brushed away the questions.
Later in a separate ABC TV interview, Mr Burke reluctantly said: "My expectation is he'd remain the candidate."
Mr Feeney will face an uphill battle to ward off a Greens challenge to the Melbourne seat which he holds on a margin of just 1.03 per cent.
He famously forgot to declare a $2.3 million investment property in Melbourne last year, and accidentally left confidential opposition briefing notes in a television studio following a gruelling interview.
Meanwhile, the argy-bargy over citizenship is expected to continue on Thursday - the last scheduled sitting day of federal parliament for the year.
Leader of the House Christopher Pyne said the government is unlikely to refer any further MPs with citizenship doubts to the High Court this year unless it can win over an independent MP's support.
The government is short one vote, with John Alexander soon to face a by-election in Bennelong.
Labor sought to end the citizenship fiasco on Wednesday, gaining the support of five crossbenchers to bring on a motion to refer four ALP members, four coalition MPs and one independent to the court.
However, with the vote tied 73-all Speaker Tony Smith used his casting vote to defeat the motion.
The government is seeking to use Senator Gallagher as a guinea pig case in the High Court to smoke out three of her lower house colleagues with similar citizenship woes.
"If Katy Gallagher is disqualified, those three members should resign," Mr Pyne said, referring to Justine Keay, Josh Wilson and Susan Lamb, who also have UK citizenship.
The High Court is due to go on a summer break from December 15 and is slated to return February 5.