Sydney: Australia's deputy prime minister has easily won a crucial by-election triggered by a dual-citizenship crisis that threatened the ruling coalition's grip on power.
Barnaby Joyce's emphatic re-election in the Saturday poll brought relief to a government which lost its slim parliamentary majority over the citizenship saga, and as it battled falling voter support and internal division.
"This has been a stunning victory," Prime Minister Malcolm Turnbull told supporters late Saturday in Tamworth, a city in Joyce's largely rural seat in New South Wales state.
"Barnaby Joyce has been re-elected member for New England with what appears to be the largest swing to the government in the history of by-elections in Australia."
Counting was ongoing but Joyce had so far picked up 64.6 per cent of the vote, with his closest rival labour's David Ewings at 11.3 per cent.
Several members of the ruling Liberal-National coalition were turfed out of their seats after the High Court in October reaffirmed a constitutional provision barring dual citizens from serving in federal parliament.
In the lower House of Representatives, where the coalition held a narrow one-seat majority, Joyce and former tennis star John Alexander had to recontest their seats in by-elections.
Joyce had automatically acquired New Zealand citizenship through his father, and renounced his Kiwi nationality to allow him to run again.
Alexander resigned from parliament after saying he was most likely a dual British citizen, but it was revealed later that it was unclear if he was even entitled to UK nationality.
The loss of Joyce and Alexander pending the by-election outcomes cost the government its majority, although Turnbull said he could continue ruling with the support of independents.
Alexander, whose by-election is on December 16, could restore the coalition's majority with victory, but faces a tougher fight than Joyce for his Bennelong seat in Sydney where the main opposition labour Party hopes to capitalise on Turnbull's problems.
Voter support for Turnbull has eroded in recent months, with the Liberal leader having to bat away calls for him to step down, even from within the coalition.
Dissatisfaction from Turnbull has stemmed from frustration with the dysfunction in Canberra, as borne out by the citizenship chaos, as well a perceived lack of leadership from the prime minister.
Bickering within the coalition has overshadowed some of his government's achievements and prompted questions over Turnbull's ability to bring the parties together.
But Joyce, leader of the National Party, reaffirmed his support for Turnbull as prime minister late Saturday, saying Australia needed "someone who has the skill set of this fella here".
"Running a country is a little bit harder than running sheep through a gate," Joyce said as he stood beside Turnbull.
"Some don't agree with him, put that aside, ask a clear question: Who do I want running the country? Malcolm Turnbull or (labour leader) Bill Shorten?... I'm going with this one."
Turnbull's headaches are set to continue next week, with a self-imposed deadline of December 5 for all parliamentarians to disclose their citizenship status that could further destabilise his government.
The Australian leader told Sky News Sunday he was confident none of his coalition members "are ineligible or could be reasonably argued to be ineligible" to sit in parliament.
The dual citizenship rule was originally inserted into the constitution to ensure parliamentarians were loyal solely to Australia.
However, critics say it is out of step with the modern reality of the country, where half the population are either foreign-born or the children of immigrants.