Malcolm Turnbull has told coalition colleagues a double-dissolution election is a "live option".
But it was reasonable to expect an election would be held between August and October when it was due.
The prime minister's comments were made on the first sitting day of parliament for the year, as he sought to win support for laws to reinstate the building industry watchdog.
The government already has a trigger for an early election of the lower house and full Senate - a clean energy bill - but the blocking of the Australian Building and Construction Commission bills could give it another more potent reason for a double-dissolution.
The restoration of the anti-corruption body was crucial not only for the building sector but taking off a handbrake on the Australian economy, Mr Turnbull told a partyroom meeting on Tuesday.
The government cannot hold a normal general election for the house and half-Senate before August 6, but before then a double-dissolution election or a house-only poll are possible.
He said it was an election year and the coalition "must win and win well", cautioning colleagues against "complacency or hubris".
The prime minister welcomed the entry of state premiers into the tax debate, saying all options had been considered by the government - indicating a GST rate rise remains on the table.
Greens MP Adam Bandt said Mr Turnbull had become desperate.
"The government is resorting to threats now to senators to say you might lose your job if you don't vote for our legislation, so you better vote for it," he told reporters in Canberra.
Independent senator John Madigan said it was like holding a gun to the heads of senators.
"I vote on the merits of legislation according to its impact on working Australians," he said.
Labor leader Bill Shorten used the start of parliament on Tuesday to unsuccessfully move a motion comparing Mr Turnbull's past rhetoric on climate change, same-sex marriage and a republic with his inaction on the issues as prime minister.
"Malcolm Turnbull has sold out everything he's ever believed in to get this job," he told parliament.
The opposition sees this as a weak spot for the coalition ahead of the election.
Meanwhile, the Greens had a lengthy planning meeting in Canberra to discuss the federal election.
The party believes it can hold its Senate seats in Victoria, Western Australia and Tasmania.
The NSW seat held by Lee Rhiannon remained winnable, but the vote was soft in Queensland and South Australia.
In the lower house, the Greens will be targeting the Victorian seats of Batman and Wills, as well as the NSW seats of Grayndler and Richmond - regions where the party made gains in the state election.
Government frontbencher Steve Ciobo says the ABCC bill would provide the government the choice of an early poll.
"We will go to an early election if we have to because unfortunately if the crossbench continues to say no, well that's an option," he told ABC radio.
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