>>tooman+(OP)
Yes, it's a two-party system, but because voting is mandatory, it means that the overwhelming majority of people (who are largely centrist with differing flavours), electorally punish politicians that stray too far from the political centre. At the same time, the "loony fringes" have much less relative voting power compared to the overwhelming majority. Remember, in voluntary voting regimes, its the loonies that are most invested in getting out the vote, whereas a majority of reasonably centrist people are more likely to think, "Why bother? My vote won't change anything". If any Australian politician or party promotes voluntary voting BEWARE!