The Turnbull government has been plunged into turmoil and will be forced to stave off attempts to establish a banking royal commission as the Opposition declares Australia is now engulfed in a “minority government” crisis.

Barnaby Joyce, who was among five politicians disqualified over dual citizenship on Friday, began his campaign with an early advantage  after his political nemesis, Tony Windsor, ruled out a run for the seat of New England.

But the former Deputy PM hinted that Mr Windsor would not be entirely absent from the campaign most expected to turn ugly, saying that his arch rival would still be “in the background” if not in the “foreground”.

Following the court’s decision, Labor declared the government was in crisis, with deputy leader Tanya Plibersek saying “this means that Australia now has a hung parliament with a minority government”.

“Every decision made by both Barnaby Joyce and Fiona Nash since October last year is under a legal cloud,” Ms Plibersek said.

Mr Joyce will fight a byelection on December 2. Photo: AAP

But Prime Minister Malcolm Turnbull claimed the government still had a majority, noting he could also rely on support from the crossbench.

By Friday night, it was still not clear who would take Mr Joyce’s role as Deputy PM, nor who would serve as acting prime minister if Mr Turnbull were to leave the country.

The PM will travel to Israel for five days , leaving on Monday, Sky News reported on Saturday. The Prime Minister’s office did not respond to a request for comment.

Mr Turnbull said the election would be held on Saturday December 2.

He said Mr Joyce was approaching voters “with enthusiasm, determination and humility”.

“I’m confident that with that combination of capabilities he will win once again the support of the people of New England,” Mr Turnbull said.

Mr Joyce apologised to voters in his seat of New England for being subjected to a byelection and told media on Friday he had expected he may lose the court case, despite statements to the contrary and choosing to stay in cabinet while the court considered his case.

“I was always prepared for this outcome. I don’t actually stand here totally surprised. I always expected that this was going to be a tough game,” he said.

Two ministers gone, one returns

Friday’s dramatic court ruling robbed the government of two cabinet ministers in Mr Joyce and Nationals deputy Fiona Nash, but a third – Nationals senator Matt Canavan – was reinstated.

Senator Canavan, who stepped aside over his possible Italian citizenship, was sworn in as Resources Minister on Friday afternoon, while Mr Turnbull announced he would take over Mr Joyce’s Agriculture and Water Resources portfolios.

Labor’s chief tactician Tony Burke would not rule out introducing a no-confidence motion in the government, and indicated that the Opposition was likely to spark a parliamentary fight on issues such as a banking royal commission.

Labor’s Tony Burke is the Opposition’s chief tactician. Photo: AAP

Crossbench senator Bob Katter, who is understood to be working on a bill for a banking royal commission with maverick Nationals MP George Christensen, flagged on Friday he would pursue that goal in Parliament.

“Just remember I’m one of the six most powerful people in Australia at the moment, and won’t I be enjoying it,” Mr Katter told reporters.

Greens MP Adam Bandt immediately said he would not “prop up” the Coalition, but Independent MP Cathy McGowan’s promise of confidence and supply should allow the PM to see off any push to topple his government.

Mr Windsor said he would stay out of the race for New England because his wife had urged him against fighting another campaign, noting his last unsuccessful bid for the seat had been personally taxing.

Tony Windsor ruled himself out of the New England contest on Friday. Photo: AAP

“I actually love elections, I’ve enjoyed the eight that I have contested, but my wife doesn’t and she had a pretty rough time last time with the tactics and strategies that were used, not only against me … but also against the families,” he told the ABC.

Mr Windsor said he would consider campaigning for a strong independent candidate who would challenge the government on issues such as the NBN and renewable energy.

Mr Joyce immediately kicked off his campaign on Friday, hosting an event at East Tamworth’s Longyard Hotel, asking voters to allow him to “continue my work in this great electorate”.