Xenophon goes back to the future

Federal parliament will lose one of its craftiest dealmakers when independent Nick Xenophon quits the Senate for another tilt at South Australian politics.

The politician who has shared the balance of the power in the upper house since 2008 was instrumental in securing parliament's approval of the Rudd government's $42 million economic stimulus package - in the wake of the global financial crisis - a year later.

His vote - a reversal of his initial position - came with a $900 million price tag for water projects in the Murray-Darling Basin.

The senator's most recent deal - and possibly his last - involved the Turnbull government's overhaul of media ownership laws.

He garnered $60 million to fund an innovation package for regional and small publishers that included 200 cadetships and grants to adapt to digital technology.

In return Senator Xenophon and his NXT colleagues backed changes to pre-internet laws that had governed how many media outlets one proprietor could own in a single market.

In between, the wily operator convinced the Gillard government to make pre-commitment technology mandatory for poker machines.

He controversially supported the Abbott government's re-introduction of temporary protection visas and its direct action plan to combat climate change.

The Xenophon vote also helped stymie a raft of tough measures contained in the Abbott government's 2014 budget, most of which remained in legislative limbo until dumped by the Turnbull government earlier in 2017.

In 2015, he backed changes to the way Australians elect their senators prompting two crossbench colleagues - John Madigan and David Leyeonhjelm - to accuse him of "political trickery of the highest order".

Nine months later, and following a double-dissolution election, Senator Xenophon was back in parliament for a third term but this time with two NXT colleagues in the upper house and another in the House of Representatives.

A year later, and before Friday's announcement, the senator was facing the possibility of being ruled ineligible to sit in parliament.

Doubts over his citizenship status - his mother was born in Greece and his Cyprus-born father held a British passport - will be adjudicated by the High Court next week.

Until a ruling is made the senator intends remaining in federal parliament.

After that, he'll make a run for a lower house seat in the SA parliament in 2018.

The master of the one-liner, Senator Xenophon likened that challenge to climbing Mount Everest without oxygen.