Coalition frontbencher Mitch Fifield has refused to say whether key industrial relations legislation will be debated in the Senate before the end of the year.

The Australian Building and Construction Commission (ABCC) and the Registered Organisations bills triggered the double dissolution election called by Prime Minister Malcolm Turnbull earlier this year.

But passing them may be difficult — as the Senate will be reshaped by the Government’s decision to ask the High Court to review the election of Family First’s Bob Day and One Nation’s Rod Culleton.

Mr Day quit the Senate last week and will not be replaced for some time, while Senator Culleton has said he will refrain from voting while his election is being questioned.

The prime minister denied the Senate was “chaotic” on Thursday. Photo: AAP

Senator Culleton had been convicted of an offence carrying a jail term of one year or more at the time of the election, which may make him ineligible to sit in the Upper House — despite the fact the conviction has since been quashed.

He pleaded guilty last month to a charge of larceny, after he stole the key to a tow truck in 2014.

South Australian crossbench senator Nick Xenophon has said he was surprised the Federal Government decided to join in a High Court action against Senator Culleton.

“I would have thought it would be more provocative than anything else,” he said.

The Government will need to win eight of the nine remaining crossbench votes to pass legislation on the ABCC and Registered Organisation bills if Labor and the Greens are opposed.

The bills are not scheduled for debate next sitting week, one of the three left before year’s end.

Senator Fifield refused to be drawn on the timing, despite repeated questioning.

Wong says Government, Prime Minister ‘paralysed’

The Senate will vote on some key legislation when it returns next week, including the bill required to hold a plebiscite on same-sex marriage.

When asked on the legislative agenda yesterday, Attorney-General George Brandis said the Government was pushing ahead.

“I as Attorney-General have some important counter-terrorism legislation that can’t be delayed,” he said.

“There is the industrial relations legislation, so the Government will be undeterred in prosecuting its agenda.”

Penny Wong was scathing of the government’s current position. Photo: AAP

But Labor’s leader in the Senate Penny Wong said the Government was “paralysed”.

Senator Wong said Mr Turnbull went to a double dissolution election over the industrial relation bills.

“He said they were the most important economic reform,” she told the ABC.

“Well, we’ve got the IR bills not on the agenda, a government that doesn’t know whether it’s going to bring them back or not.

“We’ve got a government and a Prime Minister that really is paralysed and I think the Senate program reflects that.”

-ABC