Australians, like New Zealanders, have been asked to think about changing the way they vote their federal Government into power.

But unlike New Zealand, the debate has barely pushed itself above the horizon of a green paper on electoral reform released last November, and about 100 submissions that show no inclination to move away from the systems laid down in the Constitution.

Instead, most argue for or against the present requirement of compulsory voting and other refinements within the existing systems: preferential voting for the House of Representatives, proportional voting for the Senate.

Any major overhaul would not be easy in any case: under the Constitution this would involve a referendum requiring a double victory - an overall national majority of voters, and a majority of voters in a majority of states.

Apart from the issue of compulsory voting, there has been no public passion for change.

In 1983 a joint parliamentary select committee considered changing to proportional representation in the House, but concluded that the balance between responsible government and democratic representation was best served by the existing system.

And after each federal election the joint standing committee on electoral matters conducts an inquiry to receive public submissions and recommend any improvements. None has proposed radical change.

Australians feel comfortable with a voting system that continues to be supported by most politicians, academics, analysts and public advocates.

Their parliament consists of two chambers: the House of Representatives, which comprises MPs from each of the states in proportion to their numbers of voters; and the Senate, the house of review whose Senators are divided among the states in equal numbers. The Australian Capital Territory and the Northern Territory each have two Senators.

Under the Constitution, the number of MPs in the House must number, as closely as possible, twice the number of Senators.

The present House has 150 members elected from single-member constituencies.

At an election voters are required to list their preferred candidates in order of preference.

If one candidate does not receive more than 50 per cent in the first count, the candidate with the lowest number of votes is excluded and the votes distributed among the remaining contenders according to the preferences listed on ballot papers.

The process continues until one finally prevails.

Senators are elected to represent states rather than single electorates, using proportional voting intended to ensure that the number of seats each party wins closely matches the number of votes it has received.

* The MMP referendum is to be held at the 2011 General Election.
* If the majority reject the referendum, a second binding referendum will be held with the 2014 General Election.
* This will ask voters to choose between MMP and the option chosen in the first referendum.
* Australians have also been asked to think about changing the way they vote.