Senior Turnbull government ministers from South Australia have wasted no time trying to discredit Nick Xenophon after the senator announced he will quit federal parliament for another run at state politics.
The Senate powerbroker, whose future in Canberra was already under a cloud given constitutional questions over his citizenship, has likened the move to climbing Mount Everest without an oxygen tank.
"This will be the toughest political fight of my life," he told reporters in Adelaide on Friday.
"But I'm up for that challenge because I love our state, our people and I believe that if you are in politics you should be there to make a difference."
Cabinet minister Christopher Pyne took to social media to argue "a vote for Xenophon risks 20 years of Labor".
Education Minister Simon Birmingham labelled Senator Xenophon's exit a giant publicity stunt.
One Nation senator Malcolm Roberts, who is also facing possible eviction from parliament following the High Court citizenship case, was quick to dance on his old foe's federal political grave.
Senator Roberts said it was "wonderful" the South Australian crossbencher was bowing out.
"Now he'll be able to get out of horse trading and he'll be held accountable in South Australia," he told Sky News.
But Greens senator Sarah Hanson-Young wished her fellow South Australian good luck.
"We need more non-major party MPs in lower houses chambers across the country. More diversity in houses of government is good for democracy," she said.
Senator Xenophon said he couldn't fix South Australia's problems in Canberra without first fixing the broken political system at home.
He has spoken to his three federal Nick Xenophon Team colleagues, who have supported his decision to stand in the seat of Hartley.
"It's where I shop, it's where I live, it's where I've been for decades," he said.
"I am a true local."
Labor leader Bill Shorten congratulated Senator Xenophon on his decision, but not without sticking the boot in over his dealings with the Turnbull government.
"He's a very decent and pleasant fellow to deal with, although I do understand that Nick Xenophon has done more dud deals with Malcolm Turnbull that anyone ought to put up with," Mr Shorten told reporters in Mackay.
Mr Shorten couldn't resist a few of his infamous zingers when asked what Nick Xenophon's bloc of senators ought rename themselves.
"The party who vote for the government whenever the government needs a vote?" he suggested.
Senator Xenophon served in state politics between 1997 and 2007 before moving to the federal upper house.
The Australian Industry Group said Senator Xenophon would be a real loss to federal parliament.
"His approach has always been consultative, hard-headed and practical," chief executive Innes Willox said in a statement.