More than two decades ago, running on a "No Pokies" platform, Nick Xenophon burst onto South Australia's political stage, pulling stunts and, more importantly, votes.

The so-called 'X factor' went on to become a major influence in subsequent state and federal elections — that is, until last year's disastrous attempted return to SA Parliament.

At his peak, Mr Xenophon and his NXT candidates commanded more of the Senate vote than Labor.

He also harvested support from 'small 'l' Liberals', the Greens, and a raft of other hopeful minor parties.

For Adelaide University politics professor Carol Johnson, the big unanswered question in this federal election is — what happens to those Xenophon voters and their preferences?

"[Nick Xenophon] is someone who ran on a populist agenda that actually harvested votes from the major parties and it's not at all clear where those preferences will now go," Professor Johnson said.

"We know last time that both the Greens and the Liberals lost a Senate spot to him."

Professor Johnson said Nick Xenophon did well to harvest votes from major parties. ( ABC News: Simon Royal )

Since then, NXT has had a change of name, ditched the reference to its founder and adopted the arguably less-catchy moniker "Centre Alliance".

Professor Johnson said the party was currently polling around the same level of support as the Greens.

However, the Centre Alliance is largely untested in its own right.

Only one MP has won an election under the Centre Alliance banner, Rebekha Sharkie.

Last July, Ms Sharkie saw off Liberal candidate Georgina Downer in a by-election for the Adelaide Hills seat of Mayo.

Compared to the crowd of candidates fielded by Mr Xenophon in the 2016 election, Centre Alliance is running in just three Lower House seats, including Mayo, and offering two Senate candidates.

Centre Alliance MP Rebekha Sharkie at a polling booth for the Mayo by-election. ( ABC News: Isabel Dayman )

Rebekha Sharkie is clear — she does not put her highest priority on leveraging her appeal to help other candidates.

"I work well with our candidates, I've known them a long time and I'll do everything I can to support them," Ms Sharkie said.

"I will always be about Mayo. This is my community. I don't stand in the Parliament as Centre Alliance, or Rebekha Sharkie.

"I stand in the Parliament as the Member for Mayo and I've always been very clear — this is my stomping ground."

Pyne was an influential 'fixer' who will also be missed by many

It is not just Nick Xenophon who will be a notable absence from the campaign trail.

For the first election in a generation, Christopher Pyne is not on the ticket as the Liberal Party's candidate for the seat of Sturt.

Professor Johnson said he would be missed because he was an influential, moderate South Australian voice in successive Coalition governments.

"He made considerable efforts to try and secure industries for South Australia and to shore them up, particularly defence industries, but other areas as well," Professor Johnson said.

"He's actually played a significant role in terms of the benefits South Australia has got from a Coalition Government."

Professor Johnson said Christopher Pyne was an influential voice in Government. ( ABC News: Marco Catalano )

However, Professor Johnson argued, in a democracy, there was a bigger picture than the practical matters of jobs, the economy and taxes.

"An eastern states columnist once referred to Christopher Pyne as 'the most annoying man in Australia', but he is actually someone many South Australians are perversely quite fond of," Professor Johnson said.

"He is someone who is colourful, he can provide a bit of vaudeville, to use a Paul Keating phrase, and he is also someone who doesn't entirely take himself seriously.

"That's something people have responded to, even those who didn't like his politics."

Professor Johnson argued those more theatrical qualities were, in fact, an antidote to one of Australian politic's most pressing problems — the disinterest, disengagement and distrust many people feel for it.

"It does matter if all our politicians appear to be robotic, if they appear to be lacking in character, if they appear to be continually on message, " Professor Johnson said.

"We need politicians who liven things up, we need politicians who voters find interesting, because one of the main problems in mainstream politics is keeping voters engaged and interested."

Undoubtedly both Christopher Pyne and Nick Xenophon could never be accused of being to everyone's taste.

But, in an increasingly bland political world both men brought much needed flavour.