Malcolm Turnbull is taking a big gamble on the legitimacy of two of his senior ministers staying in cabinet that he wasn’t prepared to take five weeks ago.

It’s a gamble that could see major decisions challenged in the High Court if signed off by Deputy Prime Minister Barnaby Joyce and Regional Development Minister Fiona Nash, who could yet be found to have been ineligible for Parliament because of dual citizenship.

At the end of July, another Nationals cabinet minister, Matt Canavan, stood aside from his Resources portfolio and, while remaining in the Senate, refrains from voting. He did this after discovering his mother had signed him up as an Italian citizen.

In July, a rather smug government clearly thought his case would be unique. After all, it was not as sloppy as the Greens party that carelessly lost two senators to the same rules.

Senator Canavan, a loyal National, still maintains his decision to stand aside was all his own work. Still, it was not without encouragement from the Prime Minister who, after a discussion with the senator, thought it was prudent for him to go to the backbench.

At the time, the office of Nationals leader Mr Joyce was briefing that the decision was also prompted by concerns over section 64 of the constitution which puts a three-month time limit on ministers if they are no longer in Parliament.

No use pushing the government’s luck too far was the rationale. Those concerns are no mere nicety.

Numbers game now guiding PM’s decisions

Sydney University Law professor Anne Twomey backs the prudence taken by Senator Canavan and Mr Turnbull back then.

What has changed, of course, is the government’s now parlous state in the House. If Mr Joyce refrained from voting, its majority would disappear.

Liberal backbenchers are furious that Mr Joyce has not quit the ministry.

The latest Newspoll is heavy evidence that the mishandling of the citizenship fiasco has cost the Coalition dearly. And if the High Court finds he is ineligible, the government’s crisis could yet deepen.

Attorney-General George Brandis assures us that everything is under control. He times any ineligibility from the Court’s decision.

The status of Senator Fiona Nash will be decided by the High Court. Photo: AAP

Ms Twomey − like that other eminent lawyer, the Prime Minister five weeks ago − is not so sure.

The Greens aren’t so sure either. Acting Deputy Leader Adam Bandt says any decision Mr Joyce makes to give the giant Adani mine $1 billion while he is in constitutional limbo, will be challenged.

At the very least, the High Court may be asked to rule on precisely when the ineligibility would have triggered the section 64 ministerial validity period.

Surely it would have been cleaner and safer for Mr Joyce and Senator Nash to stand aside like their colleague, Senator Canavan?  However, a panicked government, as last week demonstrated, is not thinking clearly at the moment.

Like some kind of high roller, the Prime Minister is gambling on the judges of the High Court agreeing with him that Mr Joyce, for one, is eligible and always was.

There are indications Mr Joyce himself is hedging his bets, putting out a campaigning video to his electorate last week telling them how wonderful he is.

There is now talk that Mr Turnbull might call an election by the end of the year to clean up the mess.

One incredulous Victorian Liberal says the speculation is just another indication the Prime Minister is getting jumpy over his hold on the top job.

The threat of a snap poll usually keeps the troops in line, but it can also spook them into precipitating action.

Just ask Julia Gillard.

Paul Bongiorno AM is a veteran of the Canberra Press Gallery, with 40 years’ experience covering Australian politics. He tweets at @PaulBongiorno

For more columns from Paul Bongiorno, click here