Turnbull seeks Senate voting system change

Senate election changes will put power back into the hands of voters and end backroom preference deals, Prime Minister Malcolm Turnbull says.

The government on Monday rushed legislation into parliament that will allow voters to cast preferences above the line on Senate ballot papers.

Voters now can only validly put a "1" in a box, with preferences flowing via a group voting ticket lodged by a candidate or party.

These preference flows are determined by deals done between parties and, in more recent times, so-called preference whisperers working with micro-parties.

Under the proposed system, which Mr Turnbull wants in place for the next election, voters will be able to cast preferences up to the number of Senate vacancies being filled in their state or territory.

"What these changes will do, what they seek to do, is to ensure that Australian voters determine where their Senate votes go," he told reporters in Canberra.

The Greens have given their in-principle support, but are waiting to see the details.

Opposition Leader Bill Shorten said he wanted to see the details of the legislation, which will go to a brief inquiry by the parliament's electoral matters committee.

But Labor senator Sam Dastyari described it as a "complete rort".

"The Senate is a better place when more diverse voices are being heard," he said.

Liberal Democrats senator David Leyonhjelm said there could be retaliation against the coalition in the form of minor parties uniting to campaign in marginal lower house seats.

He said the changes would disenfranchise the one-quarter of Australian voters who opt for minor parties and independents over the major parties.

It would also mean the Senate would be permanently gridlocked between Labor, the coalition and the Greens.

At the 2013 election, Australian Motoring Enthusiast Party candidate Ricky Muir won his Senate seat with less than one per cent of the primary vote, due to the complexities of preference swaps.

Election analyst Antony Green said the coalition would find it easier to win three seats in each state at a half-Senate election while Labor would ordinarily win two and battle with the Greens for the sixth seat.

Palmer United Party senator Dio Wang said the new system was merely "political tactics" by the government and it would have been better to limit preferences "below the line".

Independent senator Nick Xenophon said it would bring an end to "bizarre" preference deals, giving the example of how Labor preferences saw the election of Family First's Bob Day in South Australia.

"It will give minor parties a fighting chance," he said.

The introduction of the laws has increased the prospect of Mr Turnbull calling an early double-dissolution election.