The citizenship declaration process that in theory, was supposed to clear up the section 44 mess once and for all, has simply ushered in a new round of fighting and uncertainty. Of both major parties trying to out outrage each other, even though they both have MPs with citizenship question marks.

Amid this, the only truly fresh name to emerge from the piles of paperwork MPs submitted to the House of Representatives on Tuesday night, was Labor's David Feeney.

Feeney – who has enjoyed only brief and junior stints on the frontbench – will not necessarily be a household name. But he is well known in Canberra and exquisitely well known within Labor circles. Before he was elected to Parliament, Feeney held various ALP positions, including assistant national secretary and was a high-profile factional dude. Although they aren't quite as tight these days, he rose through the ranks with Bill Shorten and has been "thick as thieves" with the Labor leader. Feeney was also one of the faceless men right in the middle of it all when Julia Gillard toppled Kevin Rudd.

Feeney has been a member of Parliament for a decade now. He was elected as a senator for Victoria in 2007 and in 2013, his ambitions took him to the lower house, where he inherited the north Melbourne seat of Batman from Martin Ferguson.

On Tuesday, almost five months after Scott Ludlam kicked off the citizenship saga (announcing he was a surprise New Zealander), Feeney revealed he couldn't find the paperwork to prove he had renounced his British citizenship 10 years ago. In a tortured explanation, Feeney conceded he was still trying to to access "historical electronic documents ... those searches are ongoing".

So the High Court looms for the MP, with a byelection sitting off to the side as a distinct possibility – something that has Labor freaking out. In 2016, Feeney barely held off a challenge from experienced Greens' candidate Alex Bhathal. Just over two weeks ago, the Greens romped it in against Labor in the state byelection of Northcote, which takes in some of Batman.

If the Liberals decide not to run (denying Labor their preferences), then, as one Labor MP says: "we're in deep shit".

Labor insiders are puzzled and stunned that Feeney could stuff up such a major piece of paperwork. Not only is he regarded as an extremely smart man, but the ALP prides itself on the rigorous checking and legal advice that underpins its nomination processes. MPs are required to resubmit their credentials before each election, making it all the more puzzling that Feeney's situation could have repeatedly slipped through the gaps.

But then Feeney and paperwork do have a troubled history.

Back during the 2016 election campaign, Fairfax Media revealed he had failed to declare a $2.3 million house to Parliament's register of members' interests. Feeney unconvincingly put the error down to a "maelstrom of events". He then did further damage to the Labor campaign cause by leaving confidential ALP briefing notes in the Sky News waiting area after an interview (in which he also failed to answer questions about Labor policy).

Some Labor MPs believe if it were to come to a byelection, Feeney would need to think long and hard about recontesting the seat. He now has a track record of questionable administrative decisions in an electorate that is increasingly going Green, in part because of a distaste for the way the major parties do politics. While New England voters did not want to punish Barnaby Joyce for what they saw as an annoying quirk of the constitution, don't expect the people of Batman to be as forgiving.

Feeney's stuff-up also has wider implications for brand Shorten. With Sam Dastyari and now Feeney, the Labor leader is finishing the parliamentary year on a slow clap. Both cases not only reflect unkindly on the individuals involved, they cast an unflattering light on Shorten's judgment and the people he hangs around with.

Some senior Labor figures are aghast Dastyari was not cut completely loose by Shorten last week. The NSW senator may have lost some minor party positions as a result of his Chinese connections, but he continues to sit in the upper house, drawing both his parliamentary salary and daily innuendo from the government.

In the case of Feeney, his inability to prove something as basic as his citizenship status makes a mockery of Shorten's braggy declarations Labor MPs were in the clear on this one. On Wednesday, Shorten admitted he was "frustrated" by Feeney's stuff-up. But it's too little, too late.

The major parties are still scrambling to capture the moral high ground on the citizenship debacle, determined to prove one side is worse than the other. Feeney's situation shows they both have MPs who should have known and done better, and party processes that should have picked them up earlier.

Continuing to argue over who is more at fault here is not only pointless. It's really boring, too.