Nick Xenophon, the master of the stunt, is about to indulge in one more before he leaves the Senate for a run at ruling the South Australian roost from its crossbench.

After his shock announcement that he’s about to quit federal parliament, Xenophon is off to the US where, early on Monday morning Australian time, he’ll appear with Australian Ugg boot manufacturer Eddie Oygur to protest outside Deckers Outdoor Corporation headquarters in Santa Barbara.

The small business of “Aussie battler” Oygur is being sued for an alleged breach of trademark of the word “Ugg” and the boot’s patent design.

They’ll have with them, according to the pre-publicity screed from Xenophon’s office, “a flock of sheep”. It’s all about pulling wool over consumers’ eyes and fleecing Eddie, you see.

It’s typical Xenophon, an extraordinarily popular and populist politician who specialises in the corny as well as the canny.

Xenophon insists his resignation is not influenced by the cloud over his parliamentary eligibility – the High Court next week considers his, and other MPs’, dual citizenship. If that went badly for him, he’d be out of the Senate anyway.

We can accept his word. Not only do colleagues say he’s been chewing over the possible change for months – although the actual decision is recent – but a source within the government ruefully admits there were hints that weren’t picked up at the time.

Regardless of the court outcome, the Nick Xenophon Team (NXT) numbers are safe. If he loses the case, Xenophon’s Senate spot would be filled by the next person on the 2016 election ticket – Tim Storer, who runs a trade consultancy. If his position is upheld his party will choose his replacement.

At last year’s election Xenophon went from a one-man band to having a team of three senators and one lower house member. NXT Senate support is needed to pass government legislation that is opposed by Labor and the Greens.

With a government that wants to get measures through, the NXT – like Pauline Hanson’s One Nation, with four Senate votes – is in an enormously powerful position. The difference between Xenophon and Hanson is that he usually extracts a price.

He’s a tough dealmaker, who demands concessions in return for his crucial numbers.

Government negotiators sometimes can’t quite believe what they are having to give him. Most recently he received a package worth more than A$60 million for backing the media reform bill.

Earlier, as part of a deal to pass company tax cuts, he secured a one-off payment to help with high power prices for people on aged and disability pensions or the parenting payment, costing the budget some $260 million.

Leading his SA-BEST party for the March election, Xenophon wants to extend that power to state politics – where he started, elected in 1997 on an anti-pokies crusade.

“With SA-BEST and NXT holding the balance of power in both the state parliament and the federal Senate, we will work together as a united team under my leadership to drive real change to improve the lives of all South Australians,” he said in his statement announcing his resignation, which will wait until after the High Court decision.

All the signs are SA-BEST will do well, harvesting people’s discontent with the major parties. Xenophon himself will contest the marginal Liberal seat of Hartley, where he lives.

His personal entry into the SA contest will give much more heft to SA-BEST – already with a strong vote in private polls – and strike more alarm into both Liberals and Labor. He is keeping his counsel on which side he would support in a hung parliament, so maximising uncertainty. The party will not issue preferences.

ABC analyst Antony Green predicts Xenophon’s party “will poll well enough to finish first or second in enough seats to make it very unlikely either side can win a majority in its own right”.

There will be a dozen electorates in which SA-BEST will be very competitive, according to Green. He says Xenophon’s entry will be better for the Labor Party than the Liberal Party, because “he’ll be more of a challenge in Liberal seats”.

Xenophon’s departure leaves his Canberra team with considerable uncertainty. While its numbers are preserved, it has no experienced person to step into Xenophon’s shoes.

And from what Xenophon said on Friday, he wants to keep his own feet in those shoes a good deal. “I will still be heavily involved in federal decisions,” he said. “I won’t be micromanaging but I will have a good idea of what is going on and I will be part of key decisions, particularly insofar as they affect South Australia.”

That might sound all right in theory. In practice it would be complicated, especially when there is complex legislation and difficult negotiations.

Even over the last year, there have been a few suggestions of differences between Xenophon and members of his team. The more time passes, the greater the chance of Xenophon losing touch with the federal nitty-gritty and the federal team resenting input from afar.

The leadership within parliament would have to go to one of the two other current senators: Stirling Griff (most likely) or Skye Kakoschke-Moore.

There is some uncertainty about whether Xenophon would remain overall leader of the party, as well as the state leader. His comment, quoted above, referring to “under my leadership”, suggests he would. And Griff says “we still consider him the leader of the federal party” as well as of the state party.

Immediate future arrangements will be discussed when the NXT meets on parliament’s resumption the week after next.

The longer-term questions will remain. Among them will be the name of the party for the next federal election, and whether Xenophon – even if he stays overlord of the federal party – can retain as much of a national profile when his focus becomes South Australian politics.