The truth is that in Australia - and around the world - many voters are feeling angry, anxious and betrayed. Against that backdrop, the leader who appears most trustworthy and authentic might come out ahead, writes Leigh Sales.

Sometimes the things that end up deciding elections come out of nowhere.

In 2001, John Howard looked to be heading for defeat when 9/11 turned the world on its head and suddenly, terrorism and immigration were the issues of the moment.

Sometimes the key issues are blindingly obvious long before the campaign starts, such as Tony Abbott's 2013 assault built on Labor's disarray or Kevin Rudd's 2007 promise of renewal after eleven years of the Howard government.

Regardless of the political matters of the day and whether they're anticipated or not, there's a wider context that is enormously influential to the outcome of every election and it is something much harder to qualify: the vibe. The national mood helps determine whether voters feel like giving a new leader a go, tossing an old one out or giving the incumbent a tick of approval (and sometimes a kick in the pants) for the job they're doing.

Last week, I went to an interesting lunch which made me contemplate Australia's current national mood. The talk at the table centred on American politics and foreign policy and the unexpected successes of Donald Trump and Bernie Sanders in the Republican and Democrat campaigns respectively. An American guest shared his thoughts about America's national mood and how it had contributed to the rise of each candidate. Trump and Sanders sit at opposite ends of the US political spectrum but they are tapping into the same sentiments in the electorate, albeit offering drastically different answers.

What was striking, as my American lunch companion spoke, was that his analysis had some real parallels to Australia. He said that in his country, he could identify three key moods in the electorate. The first is residual anger from the Iraq War and the Global Financial Crisis and a belief that the government let American citizens down by making poor decisions and protecting vested interests. The second is anxiety caused by rapidly changing technology and how it is evaporating many jobs, both blue and white collar. And the third is a sense of betrayal that the American Dream - a secure job, a home, a better life for your kids and a dignified retirement - is out of reach for many people as the middle class in the United States shrinks and the gap between rich and poor grows.

America is not Australia and so the analysis can only travel so far. Nor is the Australian system designed to throw up fringe dwellers such as Trump and Sanders to lead either major party (although it's not an impossibility, as illustrated by the elevation of Jeremy Corbyn to the Labour party leadership in the UK).

The pattern in Australia so far is that disenchanted voters tend to coalesce around minor and frequently short-lived parties such as One Nation, Palmer United or the Democrats. Nonetheless, if you take the three core sentiments identified among American voters - anger, anxiety and betrayal - they can clearly be tracked in the Australian electorate too.

Anger

Voters' anger in Australia is not directed at botched policy decisions or the response to a major crisis. Rather, it's about the repeated breaking of election promises and the revolving door of political leadership, both giving rise to the perception that the political class is more worried about preserving its grip on power than on what matters to most Australians.

Each of the most recent Australian prime ministers has violated voters' expectations. Kevin Rudd campaigned on climate change as the great moral issue of our time and then walked away from his emissions trading scheme. Julia Gillard vowed there would be no carbon tax under any government she led, only to reverse course. Tony Abbott promised to lead a grown-up government with no surprises, only to startle the nation with his first budget, sinking a raft of pre-election pledges.

Malcolm Turnbull's plunging personal approval rating shows that he too is already making some voters feel that he's not delivering what he advertised.

Anxiety

Like the rest of the world, Australia's economy and job market is massively affected by rapidly changing technology and that is a source of great anxiety for people who fear that their jobs may not exist in the short to medium term. We've already watched this play out in Australia with the car and textiles industries. It's happening now in South Australia with the steel industry.

What we're seeing is the only the beginning. Researchers at Oxford University believe that 35 per cent of jobs in the United Kingdom will disappear during the next 20 years and it's safe to assume the figure will be similar here. The team calculated the jobs most vulnerable to robotic takeover by assessing the skills required to perform them: social ability, negotiation, persuasion, assisting and caring for others, originality, fine arts, dexterity and the space required to work. Psychologists, managers and care givers are some of the least likely find their roles automated, as they require empathy - a hard trait to program into robots. But if you're a taxi driver, a factory worker, a pathologist or an accountant, you may be in trouble.

Jobs that involve number crunching, squeezing into small spaces, manipulating small instruments in precise ways or performing repetitive tasks are unlikely to be performed by humans for much longer. That could even include previously prestigious highly-paid work, such as surgery.

Malcolm Turnbull may cheer that it's never been a more exciting time to be an Australian but without acknowledging that for many people, it's also a time of great uncertainty and anxiety, his catch-cry tells only half the story.

Betrayal

The feeling of betrayal isn't confined to voters in America either. The middle class in Australia isn't disappearing the way it is in the United States but that doesn't mean life is improving either.

For decades, many Australians have assumed they will land a job, buy a home, raise a family if they wish and then have a secure retirement with the help of government benefits conferred in exchange for a lifetime of paying tax. There's now a dawning realisation that for future generations - and many people already in the workforce - that is unachievable.

The 2015 Intergenerational Report shows that Australia will have a growing population that lives longer, meaning a smaller tax base to pay for government services. It's almost inevitable that many things that are free now will become user-pays, including in sacred public services such as health and education. The idea of a government pension as a liveable income in retirement is already something younger people discount.

House prices in Australia escalated by 141 per cent from 1996 to 2015, putting home affordability out of reach of many people, particularly given that real wage growth has been flat. 2015 ended with the lowest wage growth on record since the series was first published in 1998.

At the moment, many Australians have not given up on home ownership and a comfortable retirement and they are clinging to that goal by running up ever higher levels of debt. Research by the Federal Reserve Bank of Australia shows that Australian households carry more debt relative to the size of the national economy than any other country in the world.

On international comparisons, the Australian middle class is doing OK. A report by the International Monetary Fund last year patted Australia on the back as one of the few "important exceptions" to the middle class contraction globally. But there are warning signs that could change. Along with the stagnant growth in real wages, income distribution figures released this month by the Australian Bureau of Statistics show that the income share of Australia's middle class shrank between 2012 and 2013 while the split going to the richest families grew. The realisation that life in the future will involve harder work, less secure jobs and less government support understandably causes people to feel ripped off and let down.

So if the nation is feeling angry, anxious and betrayed, what does that mean for the election prospects of Malcolm Turnbull and Bill Shorten? Can they learn anything from the rise of Trump and Sanders in the US?

The fact is that many of the issues fuelling the national mood - here and in the US - have no easy answer. Technology WILL cost some people their jobs. Demographic pressures WILL mean fewer dollars for governments to spend on services.

In the US, Trump and Sanders are offering broad brush and populist "solutions" to Americans' concerns. Yet the reality is, for some people there will be no fix, only adaptation. Any politician who says that can happen without pain for some voters and without a change in what the government can hope to deliver in the future is lying.

Most voters don't have the time or inclination to explore every policy issue in depth and to meticulously weigh up all the alternate paths. That's what they trust leaders should do. They want a prime minister on whom they can rely to handle the detail and think about the big picture, not just fret over how tomorrow's front page will play out or how long they can keep their grip on the top job. They want somebody running the nation who outlines what they are going to do, explains why it's necessary and then does it.

Against that backdrop, the most important qualities Malcolm Turnbull or Bill Shorten can strive to display are trustworthiness and authenticity. And in that regard, despite the fast pace of change in this era, for politicians some things never change.

Leigh Sales is an award-winning journalist and author. She is the anchor of ABC's 7.30.