Thank heavens we don't have a party like the mad right-wing British National Party. Similarly we don't want some extreme crowd to our left in our politics. Extremism encourages reaction and trouble.

For good reasons, Malcolm Turnbull has made the right decision to give the Greens no support and, in particular, no preferences.

The Greens are not totally bad. As often described, the Greens are green on the outside and red on the inside. The Greens gather a lot of their support on environmental issues.  However they also have some bad friends like the militant union left-wingers. As a result the Greens are also well to the left of Labor and they are funded and supported by the militant unions.

In office, with Labor, the Greens would be pushing to cut back Australia's security relationship with the United States. Equally a problem for us would be the Greens discouraging the US involvement in our part of the world. The Greens would cut back our intelligence agencies and the Australian Defence Force. Intelligence is vital so that we can know in advance what malignant persons or states might be plotting. And of course, given that the Greens would also cut the number of our next subs and new fighter planes, we would need to spend more dollars on defence, not less. The truth is that the Greens are way out to the left in Australian politics and they should not be given any encouragement.

The other minor parties are not in the same league as the Greens. Windsor and Oakeshott are just Labor fronts. Nick Xenophon is an opportunist in the Clive Palmer mould and he mainly votes with the Greens.

The National Party is another minor party and has become more demanding in recent years. Fortunately the Nats' demand for the recognition of local government in the federal constitution was hotly opposed by the Liberal Party.  Unfortunately the Nationals have been successful in adding more bureaucracy in an unjustified push to tighten foreign investment rules on agriculture. In the Howard years, the Nationals leadership team were rationalists and could see that opening the doors to investors is in the interest of farmers as it is to the economy more generally. Hopefully a new Turnbull will take a stronger line with his coalition party in the future.

However important the minor parties may think they are, the truth is that they remain minnows compared to the two major parties who determine much of our politics. And in turn, the two major parties, unlike the special interests of minor parties, are locked in a fight for voter support.

For this reason Labor's announcement last week that debt and deficit will be deliberately worse under Labor than the Coalition is probably the biggest policy stuff up I have ever seen in politics. For Labor to think that the announcement would be well received is hard to understand.

What planet was Bill Shorten on when he put forward this idea? Has Bill become so out of touch with public opinion that he thought that running up more and more debt is a good idea?

The pity is that Labor could have put together some savings that could have made it look as if Labor was better on managing the debt and deficit than the Coalition. It could have put real pressure on the Coalition and made a real debate between the two parties.

Instead Labor is not only raising even more tax, it is spending all of the new taxes and more. The NBN will cost billions more and Labor now must surely be feeling embarrassed that on Sunday they announced $2 billion for hospitals after claiming for more than two years that the Coalition should have spent an extra $57 billion. Labor now says $55 billion less is good enough. What a joke!

On top of Labor's immediate policy debacle, Australia still faces concerns about our ability to maintain our triple AAA rating.

Head of Treasury John Fraser said earlier this year: "I know it's self-evident, but it's important that Australia maintain its top credit rating which helps contain the costs associated with servicing public debt.

"But this rating is dependent on credible fiscal consolidation and a smooth transition to a more diverse economy."

The question now is whether Labor will be any better in the new Parliament. In government or not, will Labor follow up  the promise made by Chris Bowen in May who said on Sky News that "I'm worried to see a Budget which doesn't protect our AAA credit rating going forward" and "We want to see the AAA credit rating protected, that's very important for Australia's future."

Peter Reith is a Fairfax Media columnist and former Howard government minister.