Malcolm Turnbull's chance of bringing forward the budget by a week and calling a July election could be thwarted by the senate next week.
Both houses of parliament are scheduled to sit for three days for the last time before the May 10 budget.
But the prime minister is weighing up the prospect of bringing forward the budget to May 3 to get the first raft of budget bills passed ahead of calling a double-dissolution election.
It would also give the government a second crack at passing laws to reinstate the building industry watchdog, the failure of which would give Mr Turnbull a trigger for the double-dissolution election in July.
However, there is no guarantee non-government senators will pass a resolution, which is required to allow the earlier budget sitting.
Liberal Democrats senator David Leyonhjelm told AAP he would oppose such a move.
"I'd vote against an early budget sitting," he said.
Opposition Senate leader Penny Wong gave no assurance Labor would play ball, taking the government on its word that the budget would be delivered as scheduled.
A spokeswoman said the government had yet to propose a senate sitting week starting on May 3, noting the prime minister this week said it was committed to the delivery of the budget on May 10.
The senate will receive a committee report on the ABCC bills on Tuesday.
But the bills have not been listed for debate, the government instead prioritising senate voting rule changes.
The changes would allow voters for the first time to cast their own preferences "above the line" and give the option of not having to fill out every box "below the line" on the ballot paper.
Family First senator Bob Day says the voting changes should be deferred and the government should instead bring on the ABCC bills for debate.
But the coalition is intent on passing the voting law changes, which experts say would wipe out minor parties and independents at a double-dissolution election.
The changes are expected to pass with Greens support.
The senate will hear a valedictory speech by West Australian Labor Senator Joe Bullock and the first speech by Liberal James Paterson on Wednesday, who replaces retiring Victorian Senator Michael Ronaldson.
Inquiry reports are due on the Murray-Darling Basin Plan, temporary work visas and the defence workforce.
Treasurer Scott Morrison will introduce a bill to help start-up companies access early-stage capital, as part of the government's innovation plan.
Investors will receive a 20 per cent non-refundable tax offset based on the amount of their investment, as well as a capital gains tax exemption.
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