"Is he nuts or is he a genius?" That's the question many Australians ask about Barnaby Joyce, the new Nationals leader and deputy prime minister.

From the moment he set foot in Parliament in 2005, Mr Joyce has been anything but dull.

His outspoken, sometimes rogue approach to politics could not be more different to his calm and quiet colleague Warren Truss.

The Liberal Party will be nervously wondering whether the man, who once threatened to euthanase a Hollywood superstar's pet dogs, is orderly enough to keep the Nationals in line.

Who is Barnaby Joyce?

Mr Joyce was educated by Jesuits in Sydney and describes himself as a social conservative who sits to the economic left of the Liberals.

During his career he has notably won back both Upper and Lower House seats, in separate states, for the Coalition.

He represented Queensland in the Senate from 2005 after winning the seat from One Nation, also running against the Liberals.

In 2013, he announced plans to run for the NSW seat of New England.

It was held with a 21.5 per cent margin by former independent Tony Windsor.

Windsor subsequently announced his retirement and Joyce went on to win the seat with a large swing.

He moved to the House of Representatives and was appointed Agriculture Minister.

After the 2015 leadership spill and ministerial reshuffle, Mr Joyce won responsibility for water resources, something he had long coveted, given his attachment to agricultural issues in the Murray Darling Basin.

He believes in free enterprise, is a staunch supporter of regional Australia and has lobbied extensively for drought support for famers, tighter scrutiny of the supermarket duopoly by Coles and Woolworths and tougher rules on foreign investment in Australian farmland.

Mr Joyce's approach to politics is different to that of Warren Truss. ( Tim Wimborne: Reuters )

The troublesome boy from Queensland

In his maiden speech, Mr Joyce dubbed abortion the "slavery debate of our time".

The bigger headlines came when he stared down the Howard government over its plan to privatise Telstra.

His position was much to the disgust of Liberal colleagues like former treasurer Peter Costello, because without Mr Joyce's Senate vote, the government could not pass the bill.

Mr Joyce argued it could leave rural Australia with inadequate communication services and his cry was strongly supported by everyone from rural residents to the "latte-sipping left".

Eventually, Mr Joyce agreed to vote in favour of the bill, after former prime minister John Howard pledged a $3-billion package designed to ensure the future of services in the country.

It did not take long for Mr Joyce to earn his reputation as a political maverick. He went on to cross the floor 19 times under the Howard coalition government.

Mr Joyce has been a controversial character since arriving in Parliament in 2005. ( Alan Porritt, file photo: AAP )

Neck on the line

While he was in the Senate, Mr Joyce earned a reputation for giving the prime minister curry and fighting publicly on issues he cared deeply about.

The Liberals campaigned against him when he ran for the Queensland Senate and as soon as he was elected, he made it clear he bore them no allegiance.

In 2005, Mr Joyce announced he would not vote for the government's controversial industrial relations reforms package because he was concerned people might be forced to work on Christmas Day and Anzac Day.

He was also worried the legislation could encourage companies to restructure in order to avoid new rules on unfair dismissals.

The government eventually agreed to a number of amendments and Mr Joyce supported the bill in the Upper House.

Two years later, he admitted he would not vote against Labor's plans to scale back the WorkChoices laws.

He fought doggedly for tighter restrictions on foreign ownership before and after the country's largest cotton producer, Cubbie Station, was sold to a Chinese-dominated consortium.

The government announced tougher rules last year.

Mr Joyce is in high demand from MPs and senators for appearances at party fundraisers. ( AAP: Lukas Coch )

A master of the media

Mr Joyce enjoys a high profile and some MPs and senators (Liberals included) go to great lengths to have him attend their party fundraisers.

He pulls a big crowd and big dollars.

Four years ago he received a standing ovation at a Liberal Party fundraiser in the wealthy Melbourne suburb of Toorak.

He loves a microphone and while some of his comments appear to be half-cocked, often they are calculated.

In 2015, he made international headlines when he threatened to euthanase Hollywood actor Johnny Depp's dogs, Pistol and Boo, after biosecurity officials learned the animals had illegally entered the country.

Mr Joyce famously warned Pistol and Boo to "bugger off back to America" and made it clear he would not make any concessions for the "sexiest man alive".

It was the perfect, headline-grabbing distraction at a time when former prime minister Tony Abbott's leadership was under great scrutiny.

He famously warned Pistol and Boo, Johnny Depp's dogs, to "bugger off back to America". ( AAP/Flickr: sandra.scherer )

Unashamedly ambitious

Mr Joyce has never hidden his ambition to lead the Nationals but he has consistently ruled out plans to challenge Warren Truss for the top job.

In 2007, he replaced Nigel Scullion as the Nationals leader in the Senate.

After the 2013 election, he was elected deputy leader of the party and became a Cabinet Minister.

The mere idea of Mr Joyce becoming Deputy Prime Minister makes some Liberals nervous.

They do not like his unpredictable approach.

Others feel that since joining Cabinet he has proven that he can behave, especially given the controlled media environment commanded by Mr Abbott's then-chief of staff Peta Credlin.

Prime Minister Malcolm Turnbull called Mr Joyce the day before the leadership spill to "feel the waters". ( AAP: Alan Porritt )

Joyce and Turnbull contrasting but complementary

Mr Joyce has much less in common with current Prime Minister Malcolm Turnbull than he did with Mr Abbott but the prime minister and Mr Joyce have been talking regularly since the leadership spill.

The Prime Minister rang Mr Joyce the day before the event to "feel the waters" but they did not talk specifically about the Nationals leadership.

Mr Joyce is willing to work cooperatively with Mr Turnbull and likes the fact they are such different men.

Others within the Coalition have come around to the suggestion their contrasting personalities and ideological positions would be complementary, making them a palatable and effective leadership team.

Mr Joyce feels that he and Mr Turnbull provide a strong "balance" that will allow them to speak to different constituencies and win more votes.

While most of the Nationals believe Mr Joyce deserves the honour of leader, a handful within the party disagree. ( ABC: Nick Haggarty )

Apprehension as Joyce moves to take over

Many Liberals have long dreaded a future with Mr Joyce as second-in-charge and for some, that sentiment remains.

Most of the Nationals believe he deserves the honour but a handful still occupy the "anyone-but-Barnaby" camp.

They think he is a loose cannon and have little respect for him.

There is angst among Queensland Nationals about the lack of senior roles now held by representatives from their home state.

But Nationals do not have powerbrokers and factions like the Liberal and Labor parties, so it is unlikely Mr Joyce will not assume the throne.

He also has the endorsement of a number of former Nationals leaders.

Supporters argue he is what the Nationals need; someone who has demonstrated they can work well alongside the Liberals but rock the boat when necessary.

There is no doubt that if successful, Mr Joyce will go out of this way to ensure his party gets noticed.