On lunch break from a Senate inquiry hearing in Melbourne Town Hall, Nick Xenophon is in a relaxed mood.

The lack of parmesan available to add to his pasta in Brunetti’s cafe momentarily deflates his upbeat bearing, but – on what is due to become a big afternoon in Australian politics – this Senate big cheese takes it in his stride.

It’s the day two Liberal MPs will move the spill motion against PM Tony Abbott, though as Xenophon tucks into his tagliatelle, that’s an hour away. Meanwhile, the antipasti for our 20 minute conversation is the PM’s rapidly mounting troubles.

“The only way around the problem is for him to change his policies,” says the popular independent senator of Cypriot heritage between mouthfuls, “and I don’t know if he’s prepared to do that. To date he’s shown an ideological rigidity that concerns me.”

“As opposition leader Tony Abbott’s mantra was ‘trust in government’, in particular the broken promises of Julia Gillard and the carbon tax, and what happens? He gets into office and he breaks all his promises and people are sick of it.”

With crossbench support in the Senate critical for the Abbott government’s legislative agenda in its first 16 months, Xenophon has been at the centre of the storm – with the major parties regularly appealing for his support.

Close to independent senator John Madigan and with evolving ties to Jacqui Lambie and the Motoring Enthusiasts’ Ricky Muir, Xenophon’s position as a crossbench powerbroker has grown in recent months, particularly after Lambie’s defection from PUP.

The media’s hyperbole over the extent of this influence is something Xenophon says is way over the mark. Annointed ‘King of the Senate’ by some, he’s characteristically dismissive of such a moniker.

“I come from the political centre, if people come to me they know they can speak to me in confidence, and trust me, and I’m never going to breach that trust.

“To be called king of the Senate is embarrassing. Anyway, I’m a republican,” he quips.

Talking of republicans takes us back to the Liberal’s leadership problems. Asked to predict where the Liberals go next, Xenophon shares what must now be Australia’s most widely held view.

“It’s almost inconceivable that Tony Abbott will lead the Coalition in the next election in 2016,” he says, before adding, “I think they can do a lot worse than draft in Peter Costello.”

Volunteering a more likely scenario, Xenophon says Malcolm Turnbull or Julie Bishop will lead the Coalition after Tony Abbott’s eventual resignation.

“The problem is Turnbull believes in an emissions trading scheme, and the party’s against that, even though I think that is a sound policy, he’s politically vulnerable there.”

Above all, it’s the policies that the Coalition needs to transform – the personalities are secondary, says Xenophon, who maintains the Abbott government’s economic crusade to ensure Australia ‘lives within its means’ has been misdirected.

“They haven’t done it in an equitable way,” he says with no small degree of passion. “They’ve let some of the wealthiest people in the country get away untouched, but the single mum with three kids takes more of a hit than someone on $300,000 a year. How is that fair?”

With Nick due back on the Senate panel in the Yarra room in a few minutes we have time for one more topic: foreign affairs. He’s been following the situation in Greece with interest.

“The vote for SYRIZA is a stunning repudiation of the old politics,” says Xenophon.

Asked if he believes if Greece’s new government can live up to expectations and overturn the orthodoxy of austerity in the EU, he’s less sure.

“The people have spoken and that needs to be respected, but I think SYRIZA will be more pragmatic than ideological when it comes to tackling some of the problems.

“All of Europe is looking to see if Greece can pull it off. I wish them well. Greece has serious problems and they need to be tackled.”

A coffee is needed before Xenophon heads back to the Senate inquiry hearing on airports and aviation security, to grill airport authorities, the AFP and ASIO on what they’re doing to keep us safe.

We call into Starbucks. The South Australian senator asks for a takeaway flat white. “What name shall I put on that?” asks the young barista who doesn’t watch a lot of news.

Doesn’t everyone know who Nick Xenophon is by now?