Donald Trump has risen to probable nominee status through an extraordinary ability to tap into the deep fears and anxieties of millions of Americans. Reuters/Scott Audette

In 1948, more than half a century ago, Harry Truman was re-elected president of the United States after pollsters had tipped a win for his Republican rival, Thomas Dewey.

That election should remind us both that polls can be wrong, but also that major parties can fragment.

Truman lost four deep southern states to Dixiecrat Strom Thurmond. This was a harbinger of the shift that has turned the American South into the bastion of the Republican Party. The electoral map of 1948 is almost a mirror image of current alignments, although the large states of the industrial mid-West remain the most contested terrain.

There are other parallels in American history to elections that unsettle the balance, which usually occur when one party nominates an outsider. This November increasingly looks as if it will be a contest between the consummate insider Democrat, Hillary Clinton, and Donald Trump, an insurgent who has laid siege to the Republican Party through sheer chutzpah.

It is mathematically possible to construct scenarios that see Trump failing to win the nomination, or Bernie Sanders finding a surprising surge in support in large mid-Western states. But neither seems likely.

That Clinton and Trump both won their parties’ primaries on Super Tuesday in Virginia and Massachusetts, where their opponents should have performed well, suggests the nominations are basically decided.

Towards November

The conventional wisdom that saw Trump being supplanted as frontrunner long before Super Tuesday now sees him losing to Clinton in a general election. As Shakespeare’s Prince Henry might remind us, the wish is father to the thought.

Yes, Barry Goldwater in 1964 and George McGovern in 1972 are often cited as examples of candidates chosen by their parties who were roundly defeated in the ensuing election. It is also the case that in the late 1970s many optimistically proclaimed Ronald Reagan was too radical – and too old – to be elected president.

Trump, possibly the most egomaniacal figure ever to contest the presidency, has risen to probable nominee status through an extraordinary ability to tap into deep fears and anxieties among millions of Americans. Due to the possibilities of modern media he has captured a political party with which he has tenuous links, and most of whose leadership dislike and fear him.

If running against the Republican mainstream has done Trump no harm in the primaries, it may prove more successful in a general election. Democrat strategists remember that up to one-quarter of nominal Democrats voted for Reagan in 1984, and are anxious about the results in states such as Michigan, Ohio and Florida that are crucial to a Clinton victory.

It is likely that sufficient Republicans will support Clinton, or at least not vote, and that black and Hispanic voters will turn out in sufficient numbers in November to carry those states where there may be significant Democratic defections to Trump.

It is also possible that Trump can mobilise enough resentment and prejudice to win sufficient votes to beat Clinton, who many Americans deeply dislike.

What it might mean for the world

If I were betting I would put my money – cautiously – on Clinton to win.

For Australia, a Clinton presidency would mean little change in its relationship with the US. Both of Australia’s major parties have had good relations with the Obama administration, and quietly backed Clinton when she pressured Obama to adopt more hawkish positions on the Middle East or towards Russia.

The impact of a Trump presidency is basically unknown, though. No serious candidate in the post-second world war period has been so unclear in their attitude to foreign policy. We know that Trump wants to stand up to Mexico, China, Iran and Islamic State; that he has a sneaking admiration for Russian President Vladimir Putin; and that his instincts fluctuate between bellicosity and withdrawal.

Clinton has a team of foreign policy advisors large enough to staff the United Nations. Trump has not revealed any of his foreign policy team. It is possible that he regards foreign policy as rather akin to establishing a hotel chain overseas – after all there are Trump hotels in Rio, Bali and Panama.

If Trump becomes the nominee there will be some Republicans who will join his team out of sheer ambition and perhaps fear for their country. But almost all of his stated goals – bombing Middle East oilfields, getting Mexico to build a wall along the frontier, ending trade deals with China – are soundbites, not policy proposals.

It is impossible to make any sensible predictions of how a Trump presidency would engage with the rest of the world. But it might be rather like suddenly discovering Putin is on our side.

Speaking with comedian Jerry Seinfeld, Barack Obama observed that a “pretty sizable percentage” of world leaders are crazy. Let’s hope he wasn’t speaking of his successor.

Dennis Altman does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Dennis Altman, Professorial Fellow in Human Security, La Trobe University

This article was originally published on The Conversation. Read the original article.