A deal between the Coalition and the Greens on Senate voting reforms has paved the way for a double dissolution election anytime from 1 July.

The government is expected to accept a joint committee recommendation for optional preferential voting below the line. Before the deal, the government had designed a bill for optional preferential voting above the line only.

The Greens have insisted that the government allow the Australian Electoral Commission time to implement the reforms – at least until 30 June.

As a result, the deal would give Malcolm Turnbull the option of a double dissolution from 1 July onwards with a new Senate voting system of optional preferential voting.

The prime minister said after consideration of the report, the government would move amendments during the debate on the commonwealth electoral amendment bill 2016 on Wednesday morning.

“These are important reforms in the public interest that will ensure election results reflect the will of voters,” Turnbull said.

“We again call on Labor to reconsider their position and to follow the considered advice of their highly regarded shadow minister for electoral matters, Gary Gray, instead of just succumbing to the pressures of the union lobby and Labor’s backroom operators.”

The deal comes after a report was tabled in parliament at 9am on Wednesday. It was the product of a “quickie” hearing, which lasted less than a day. It heard extensive evidence that the Coalition bill was flawed because it treated above the line voting differently to below the line.

As a result, the joint parliamentary committee recommended any reforms to the Senate voting system should include optional preferential voting below the line, with voters instructed to number a minimum of 12 boxes.



The committee, headed by the Liberal MP David Coleman, supported the government bill to change the Senate voting system – but only if it was amended to include optional preferential voting below the line.



The existing bill abolishes group voting tickets, the party-submitted mechanism to decide how preferences flow for supporters who simply vote above the line rather than filling in all the candidate squares below the line.



The joint committee has also recommended a “savings provision” which would ensure any ballot paper with at least six boxes numbered sequentially from one would also be considered formal.



“The capacity for a voter to express his or her preference is surely the most fundamental feature of any electoral system,” Coleman said. “The overarching goal of any electoral system must be to ensure it reflects the genuine will of the people.”

He said the current voting system fell “well short” of the fundamental goal that the electoral system should clearly reflect the will of the people.

“Preferential voting below the line is most important to ensure that voting below the line is not an extraordinarily arduous process that it currently is and acts as a disincentive to voters to vote below the line,” Coleman said.

The Coalition and the Greens are locked in a procedural tussle with Labor in the Senate to bring on the commonwealth electoral amendment bill 2016. Labor has been trying to delay the bill because it does not support the voting changes.

As the Senate tussle continued overnight, the former Liberal prime minister John Howard warned the government that the deal with the Greens could backfire on the Coalition in the future.

“The principal beneficiary of these changes is probably the Australian Greens, and that is why the Australian Greens are so strongly in favour,” Howard said. “So, I hope this doesn’t preside some kind of understanding about preferences in House of Representatives elections between the Coalition and the Greens.”

On Tuesday Labor’s leader in the senate, Penny Wong, spoke vociferously against the changes. Labor has been quoting the ABC psephologist, Antony Green, as saying the change would give the Coalition a greater chance of winning a “blocking majority”.

Green told Guardian Australia he had been taken out of context. He said Howard had won a blocking majority – 18 of the 36 state Senate seats – in 2001 and 2004. “What I said was that the changes would tend to produce the same thing as the current system,” he said.