One hundred days ago, Malcolm Turnbull was sworn in as Australia’s 29th Prime Minister after deposing Tony Abbott in a leadership spill.

As the nation gears up for the 2016 election, it remains to be seen how much longer the Turnbull honeymoon – buoyed by strong poll results – can keep rolling on.

It could be the tensions within his own party, and the deals he did to become Prime Minister, that present more of a challenge than his political opposition.

• Turnbull looks shaky on his trainer-wheels
• Turnbull pushes Japan on whaling in Tokyo
• Turnbull fends off bolshie Nationals over Macfarlane

Take a look at five tests Mr Turnbull will face in 2016.

Mal Brough

Towards the end of the parliamentary sitting year, the Opposition hammered Mr Brough with question after question about whether he asked James Ashby to copy his diary for him. Photo: ABC

In an appointment that surprised many, Mr Turnbull returned Queensland MP Mal Brough to the Ministry as Special Minister of State.

That is despite the cloud of “AshbyGate” still casting a shadow over Mr Brough.

Towards the end of the parliamentary sitting year, the Opposition hammered Mr Brough with question after question about whether he asked former Speaker Peter Slipper’s staffer, James Ashby, to copy his diary for him.

On the Nine Network’s 60 Minutes program, Mr Brough said he had indeed made the request. In Parliament, he had a different story.

The Australian Federal Police are still investigating. Mr Turnbull continues to face significant pressure over whether to keep him in such a significant role.

GST

The Government says all options are on the table, and have not ruled out lifting the rate of the GST to 15 per cent, or broadening what it covers to things like fresh food. Photo: Getty

As the old saying goes, there are only two things in life that are certain. Death and taxes.

It is the latter that is troubling governments around the country at the moment, with revenue slumping and government coffers crying out for more money.

The solution, according to the Prime Minister and his Treasurer Scott Morrison, is to implement changes to the tax system, making it more efficient.

But the issue capturing most of the attention is what that will mean for the GST.

The government says all options are on the table, and have not ruled out lifting the rate of the GST to 15 per cent, or broadening what it covers to things like fresh food.

Whatever the final policy position it will be a tough sell, made even more difficult by an Opposition steadfastly opposed to changes to the GST.

Tony Abbott and his Conservative brigade

Tony Abbott continues to make headlines, giving his opinions on military deployments in the Middle East, Islam and defending his government’s legacy. Photo: AAP

When leaving the top job, Tony Abbott said there would be no sniping from the sidelines.

But he continues to make headlines, giving his opinions on military deployments in the Middle East, Islam and defending his government’s legacy.

While the Prime Minister maintains Mr Abbott is welcome to give his own opinions on matters, there is no doubt the ghosts of prime ministers past will haunt Mr Turnbull over the summer holidays.

Combine that with commentary from some of Mr Abbott’s right-hand men, including former employment minister Eric Abetz and former defence minister Kevin Andrews, and the task of forming his own policy and legacy appears distracted.

Ian Macfarlane and the Nationals

Ian Macfarlane’s surprising announcement that he wanted to defect from the Liberals to the Nationals caused rumbles within Nationals ranks that they deserved another Cabinet position. Photo: AAP

Abbott government minister Ian Macfarlane lost his job as Industry Minister when the new PM looked for a revitalised Cabinet.

However, what he did next was surprising: he announced a desire to defect from the Liberals to the Nationals. The move was blocked by the Liberal National Party executive in Queensland.

While both parties govern in unison, and the switch in allegiances would not have impacted Mr Turnbull’s numbers in the floor of parliament, it did cause rumbles within Nationals ranks that they deserved another Cabinet position.

Mr Turnbull had already renegotiated the Coalition agreement with Nationals leader Warren Truss, and was forced to hand over the water portfolio to Deputy Nationals Leader Barnaby Joyce.

But the Nationals are hungry for more, and believe they are entitled to another position.

It has also been revealed Nationals members have embarked on something of a recruitment campaign, approaching a small number of Liberals to join the defection movement.

Same sex marriage and climate change

Same-sex marriage and climate change are two issues that may cause Mr Turnbull some headaches at the ballot box. Photo: AAP

Labor has sought to make significant political capital of Malcolm Turnbull holding on to the policies of his predecessor – particularly with regards to same-sex marriage and climate change.

Mr Turnbull has advocated for a free vote in Parliament on gay marriage. But as soon as he became Prime Minister, he backed Mr Abbott’s position, that the issue would be taken to the Australian people.

It was Mr Turnbull’s stance on climate change that brought his time as Opposition Leader to an end, when he was ousted by Mr Abbott.

Since taking back the leadership of the party, he has also kept the Abbott government’s position on a “direct action” plan to tackle climate change.

Both issues may cause Mr Turnbull some headaches at the ballot box if voters believe he has shirked his values for a tilt as Prime Minister.

– ABC