<P> The Australian federal parliament has a number of distinctive features including compulsory voting, with full - preference instant - runoff voting in single - member seats to elect the lower house, the Australian House of Representatives, and the use of optional preferential voting to elect the upper house, the Australian Senate . </P> <P> Australia has a mild two - party system, with two dominant political groupings in the Australian political system, the Australian Labor Party and the Liberal / National Coalition . Federally, five of the 150 members of the lower house (Members of Parliament, or MPs) are not members of major parties, as are 20 of the 76 members of the upper house (senators). </P> <Table> <Tr> <Th_colspan="2"> Political party </Th> <Th> Leader or sole member </Th> <Th> Members of Parliament </Th> <Th> Senators </Th> </Tr> <Tr> <Td> The Coalition </Td> <Td> Liberal Party of Australia </Td> <Td> Malcolm Turnbull </Td> <Td> 45 </Td> <Td> 20 </Td> </Tr> <Tr> <Td> National Party of Australia </Td> <Td> Barnaby Joyce </Td> <Td> 10 </Td> <Td> </Td> </Tr> <Tr> <Td> Liberal National Party (QLD) </Td> <Td> none </Td> <Td> 21 </Td> <Td> 5 </Td> </Tr> <Tr> <Td> Country Liberals (NT) </Td> <Td> none </Td> <Td> 0 </Td> <Td> </Td> </Tr> <Tr> <Td_colspan="2"> Australian Labor Party </Td> <Td> Bill Shorten </Td> <Td> 69 </Td> <Td> 26 </Td> </Tr> <Tr> <Td_colspan="2"> Australian Greens </Td> <Td> Richard Di Natale </Td> <Td> </Td> <Td> 9 </Td> </Tr> <Tr> <Td_colspan="2"> Nick Xenophon Team </Td> <Td> Nick Xenophon </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td_colspan="2"> Pauline Hanson's One Nation </Td> <Td> Pauline Hanson </Td> <Td> 0 </Td> <Td> </Td> </Tr> <Tr> <Td_colspan="2"> Katter's Australian Party </Td> <Td> Bob Katter </Td> <Td> </Td> <Td> 0 </Td> </Tr> <Tr> <Td_colspan="2"> Jacqui Lambie Network </Td> <Td> Jacqui Lambie </Td> <Td> 0 </Td> <Td> </Td> </Tr> <Tr> <Td_colspan="2"> Derryn Hinch's Justice Party </Td> <Td> Derryn Hinch </Td> <Td> 0 </Td> <Td> </Td> </Tr> <Tr> <Td_colspan="2"> Liberal Democratic Party </Td> <Td> David Leyonhjelm </Td> <Td> 0 </Td> <Td> </Td> </Tr> <Tr> <Td_colspan="2"> Australian Conservatives </Td> <Td> Cory Bernardi </Td> <Td> 0 </Td> <Td> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Political party </Th> <Th> Leader or sole member </Th> <Th> Members of Parliament </Th> <Th> Senators </Th> </Tr>

What are the four main political parties in australia