This week's Labor legislation dismantling the single desk export marketing arrangements for wheat can be viewed from any number of angles: a broken election promise, the rejection of the will of the majority, and even another step towards dismantling of The Nationals.

While the latter may seem a long bow to draw from a single piece of legislation, it is true that the single desk was one of the last pillars of Nationals policy which separated it from both the Liberals and Labor.

Having embraced free trade, rolled over on the sale of Telstra against the will of its constituency, and now having lost the argument to maintain the single desk, The Nationals now have few points of difference left in the political market place.

Which begs the question, if Nationals Leader Warren Truss is serious about the option of splitting the Coalition and going it alone - as he again suggested this week - what would separate The Nationals identity from the other parties in opposition?

Former Leader Mark Vaile went to the last election trying to separate The Nationals from the Liberals by branding the Nats as the party for the seven million regional Australians - but when it came to the crunch, voters chose Labor.

Identity and demographic change have together been responsible for the decline in Nationals' representation in the Federal Parliament.

The other alternative, of course, is the much-publicised option of merging with the Liberals to form a single non-Labor conservative party, which looks likely to happen in Queensland.

In the same way as the ideological gap has narrowed between Labor and Liberal, it has all but disappeared between The Nationals and their coalition partners.

And even if there were differences of opinion within a new party, Liberal and National party rules - unlike the Labor party - allow members to cross the floor, a la Senators Gary Humphries or Barnaby Joyce, and voice dissent without consequence. Thus, a rump of ex-Nationals members could operate within any new federal conservative party in the same way they operate currently in the joint Coalition party room.

But while The Nationals and Liberals in NSW are very close, the situation in each state is very different - in South Australia the sole Nationals MP is in Coalition with the Labor State Government.

Either all states will have to work at their own pace, or federal party leaders will have to impose a merger from the top - a messy business which would not be well received in all quarters.

The path forward is riddled with difficulties for Warren Truss, and the Liberals know they have time and demography on their side if he dallies too long.