Australians will likely be headed to the polls on July 2 with the Senate widely expected to hand the federal government an early election trigger.
MPs and senators were recalled to Canberra by Governor-General Peter Cosgrove, after parliament was prorogued in a constitutional move not used for 40 years to consider bills restoring the government's building industry watchdog.
Prime Minister Malcolm Turnbull has vowed to use a second rejection of the bills as a trigger for a double-dissolution election on July 2 - a prospect that's looking increasingly likely after several senators told parliament on Monday they won't be supporting it.
Parliament has been given three weeks to consider the bills, but there's speculation a vote could be held as early as Monday night.
If the legislation is defeated, voters will be headed to the polling booths in July - provided Mr Turnbull keeps to his word.
Independent senators John Madigan and Jacqui Lambie ruled out support while Motoring Enthusiast Ricky Muir said he didn't see much point continuing the debate given the government's unwillingness to consider his proposed amendments.
"If the government won't even consider what I believe to be reasonable amendments at least worthy of debate in this chamber then let's get this bill as it's presented to a vote.
"Then the government can proceed with what it wants, an early election."
Senator Lambie said there was a high probability the bills would be defeated, insisting she wasn't afraid of an early election.
"My vote will never be influenced by threats from this prime minister of a double-dissolution election."
Senator Madigan said the proposed Australian Building and Construction Commission would be granted coercive powers not even available to police, while construction workers would be left with fewer rights than an alleged murderer.
Independent senator Glenn Lazarus has previously indicated he won't support the legislation as it stands.
With Labor and the Greens opposed, the legislation needs the support of six of the eight crossbenchers to pass.
Independent senator Nick Xenophon said the Senate was fast headed for a vote on the ABCC.
"The government will get what it has been really secretly or not so secretly wishing for and that is for a double dissolution trigger," he told reporters.
Labor accused Mr Turnbull of misleading the governor-general over his reasons for proroguing parliament, using "propaganda" to justify restoring the ABCC.
Mr Turnbull's claim the ABCC would lead to improved productivity was a "complete untruth", based on discredited reports and figures from "cash for comment" consultancy firms, senior Labor senator Doug Cameron said.
"The prime minister misled the governor-general and he knows it."
The bills robbed construction workers of basic human rights and put their lives in danger, he said, with evidence showing a rise in workplace deaths when the commission was established by the Howard government.
The Senate has also been asked to reconsider the government's registered organisations bill, which is already an early election trigger having been rejected several times.
The government also wants the Senate to consider legislation abolishing the Road Safety Remuneration Tribunal and is willing to temporarily adjourn debate on the ABCC to deal with it.