In what will be a major shot in the arm for the government and could restore some confidence after a grim few weeks, Mr Joyce appears to have lifted his primary vote by at least 10 points, meaning after the distribution of preferences he will have as many as seven in 10 votes in the NSW seat.

That represents a swing of at least 11 per cent and possibly as much as 14 per cent on a two party-preferred basis compared with the 2016 election.

It comes despite the government's flaccid fortunes lately and the unusual circumstances of Mr Joyce losing his seat to the citizenship crisis.

"This has been a stunning victory," Mr Turnbull said alongside Mr Joyce on stage at the Southgate Inn in Tamworth. "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 byelections in Australia. And it has been a great demonstration of the strength of our coalition.

"We're getting the band back together."

To chants of "Barnaby, Barnaby", Mr Joyce said he took the victory as "a sacred duty" and vowed to do "everything in my power to make sure I honour that".

In a nod to the government's recent troubles and the fractious relationship between the Nationals and the Liberal Party, Mr Joyce gestured to Mr Turnbull and said, "I'm really looking forward to going back to work with this guy here.

"Running a country is a little harder than running sheep through a gate, I can tell you that," he said. "You need someone who's got the skill set of this guy here ... Ask yourself a very clear question: 'Do I want Malcolm Turnbull or do I want Bill Shorten?' I'm going this bloke.

"We're looking forward to going straight back into bat to serve you. We're going back to work tomorrow."

Larry Anthony, National party president, declared it a "historic occasion".

[It's] a massive swing to the Coalition, a massive swing to Barnaby. This is not just about putting Barnaby back in the Parliament, it's about putting him back in as leader of the Nationals formally, putting him back in as the deputy prime minister and putting him back in the government to support Malcolm Turnbull."

Afterwards Mr Anthony told Fairfax Media he believed the thumping win would "hit the reset button for the Coalition".

He said most New Englanders likely felt that Mr Joyce had been "unfairly dismissed" by the discovery he was a New Zealand citizen through his father in "a quirk of the constitution".

"This byelection really was not a referendum on the government, it was an endorsement of Barnaby Joyce and do we want him to represent us in Parliament for New England," he said.

"I think the flow on effect will be positive for the government."

Michael McCormack, Nationals MP and Minister for Small Business, said that "any talk of a fracture between the Nationals and the Liberals was quashed tonight".

"It was absolutely blown out of the water. This further solidifies what was already a united party."

He said all efforts would now swing behind John Alexander in the Bennelong byelection with the hope of securing a similarly strong win.

In other good news for the government on Saturday, maverick Nationals MP George Christensen confirmed he would remain in the party, apparently ending the tense standoff with the government amid reports Mr Christensen might quit, stripping Mr Turnbull of his one-seat majority.

Mr Joyce said on Saturday afternoon while winding up his campaign to retake the seat of New England he had just minutes earlier received a text message from Mr Christensen.

The message stated that Mr Christensen would stay in the party now that the government had agreed to a banking royal commission and with Mr Joyce remaining Nationals leader, given he is widely expected to win back the seat he lost because he had dual New Zealand citizenship.

It appears to put to an end weeks of speculation after an unnamed conservative Coalition MP told a journalist he would quit the party and shift to the cross-bench unless Mr Turnbull stood down as Liberal leader and Prime Minister.