03/11/2016 9:30 AM AEDT

'The Senate, As Always, Is A Many Splendoured Thing'

With two Senate seats in doubt, contentious government bills have been dropped, perhaps for the year.

Stefan Gosatti/Fairfax Media
One Nation Senator Rod Culleton has vowed not to vote on

CANBERRA -- "We take each week in the Australian Senate one week at a time".

That's how softly, softly the Turnbull Government is treading with the fate of two crucial crossbench Senate seats in doubt.

There are only three parliamentary sitting weeks left for the year, but the potentially invalid elections of, the now former, Family First Senator Bob Day and One Nation Senator Rod Culleton have thrown a delicate numbers situation in the Senate into chaos.

Both cases are to be referred to the High Court and it is not known when they will be resolved. Day has resigned over the collapse of his business interests, effective immediately, and Culleton has vowed he will abstain on "contentious bills" while his place in the Senate is being investigated.

"The Senate, as always, is a many splendoured thing. And so it is," Manager of Government Business in the Senate Mitch Fifield told ABC Radio's AM.

"We have a full legislative agenda.

"We will deal with the numbers in the Senate as they are."

It's been revealed in the Senate's draft program, released on Wednesday, that the government has left its much-wanted legislation to restore the Australian Building and Construction Commission (ABCC), the trigger for the July 2 double dissolution election, off next week's agenda.

"We are absolutely committed to the ABCC legislation and are absolutely committed to the Registered Organisations legislation," Fifield said.

But Fifield can't say if the important bills will be dealt with before the end of 2016.

"We view the legislative program one week at a time," he said.

Bills to enable the same-sex marriage plebiscite, impose a lifetime ban on boat refugees, charge a 19 per cent backpacker tax and overhaul vocational loans for students are up for debate.

The other job for Senators, when they return to parliament on Monday, is whether to approve the Government's referrals of the cases of Day and Culleton to the High Court.

Both are potential breaches of Section 44 of the Australian Constitution.

What is Section 44?

Section 44 of the Constitution sets out restrictions on who can be a candidate for Federal parliament.

It lists a number of ways a senator may be disqualified, including whether they have allegiance to a foreign power, whether they are a traitor or have been convicted of a crime.

The last clause of the section -- whether they are connected to an office for profit -- relates to the cloud over the election of Bob Day. It is murky and has not been tested.

Culleton's problem is he had been convicted of the serious crime of larceny at the time of the election. It has since been annulled and he is now protesting his innocence and is wondering what all the fuss is.

Asked how Culleton was allowed to nominate for the Senate with a conviction hanging over his head, Fifield explained the system relies on the honesty of candidates.

"The system relies upon the information the candidates provide to the Australian Electoral Commission, he said.

"This matter is before the High Court. It has been raised by an individual."

"The Attorney cognisant of that sought advice and Senate will be seeking to refer that to the High Court To make sure there is clarity."