The possibility that NXT may even win a lower house seat or two has generated unsuccessful demands that Xenophon reveal which major party he would support in the advent of a hung Parliament.

None of this may happen given the recent powerful attacks on him. There have been various targets, including his record on Senate voting reform, his allegedly protectionist, anti-free trade policies, his public campaign against an Adelaide Catholic priest for alleged sexual abuse, his alleged populism, and the apparent anonymity of the other members of his Senate team. Senior local members of the major parties, Christopher Pyne (Liberal) and Senator Penny Wong (Labor), are now called upon to explain the popularity of the NXT. They flounder around in fear of contributing to a further backlash against the governing parties they represent.

This likely electoral outcome is unprecedented because never before has the Australian federal system generated such a successful state-based regional party or team of candidates. The Canadian federal system has often been regionalised like this but not Australia. Australian parties have emerged with particular emphasis in one state, including the Democratic Labour Party in Victoria, the Australian Democrats in South Australia, the Greens in Tasmania and even perhaps the Pauline Hanson One Nation Party and the Palmer United Party in Queensland.

But these parties have also had wider national aspirations and representation right from the beginning. Xenophon is standing some candidates outside South Australia but the impression still is that his aspirations are firmly South Australian at least for now.

There have also been successful independents with a base in just one state, such as Senator Brian Harradine in Tasmania, but he was unable to build his extensive support into a team.

Xenophon's self-description and recent explanation of his policy priorities show what is old and what is new about NXT. First and foremost, in addition to being a state-based party, his project is centrist. This idea has predecessors, especially in Don Chipp and the Australian Democrats, and there have been some connections between Xenophon and the Democrats.

There was a vacuum in the centre of Australian politics after the demise of the Democrats but no other party has yet been able to fill it. The Greens are to the left and recent micro parties haven't sat comfortably between the two big parties despite some attempts, including by Clive Palmer, to perform that role. A centrist party needs not just an appropriate ideological position but a certain style. A centrist role is best accompanied by a moderate, even self-effacing, negotiating style rather than bombast.

But the centrist role has its problems because it depends on there being a large gap to fill between the two parties, one situated on the right and the other on the left. Xenophon, sounding very much like Chipp once did, told Fairfax Media that "whatever I do I would drag both parties to the centre – that would be the outcome".

That is possible on some traditional issues, like the economy and industrial relations, but is less easy for issues like border protection where the major parties behave more like cosy allies than competitors. There is a long history of the major parties looking like Tweedledum and Tweedledee and that poses practical difficulties for a centrist party.

NXT is also an unabashed state-based party, unlike the Democrats. Its first priority is a new approach to procurement policy to allow a preference for local procurement. Any pro-South Australia NXT decisions will have national consequences far beyond Xenophon's past influence on Murray Darling water policy and pork barrelling for his own state. He reckons that his approach would be "a fine balance between doing the right thing for your electorate and the right thing for your country".

This emphasis on representing his electorate should be music to the ears of those who have long wanted more responsive MPs free of party discipline. However when a whole team of senators from one state takes this approach, as the NXT team promises, its national impact is potentially huge. The impact is far greater than when a single member of the House of Representatives is responsive to their electorate rather than to their party.

His second priority is for greater transparency in government. This echoes what many government critics, including several minor and micro parties as well as independents, have been saying for years. Yet the two parties of government have always been cautious in implementing any transparency reforms and even more cautious operating them in practice. This priority will attract wide community support.

The third NXT priority is to continue Xenophon's long campaign in the SA Parliament and in the Senate for gambling reforms. Even when also advanced by Andrew Wilkie (Denison) in the House of Representatives such reforms have been bogged down because they have been opposed by vested interests in the clubs and pubs industries. With a large Senate team Xenophon will have greater leverage for his favourite cause.

Supposedly new developments in Australian politics are never entirely new. NXT brings together some policy and ideological challenges to the major parties which have around for years. But in addition to these ideas the concentration of this development in just one state, South Australia, is unprecedented.

John Warhurst is an emeritus professor of political science at the Australian National University.

John.Warhurst@anu.edu.au