From the moment 17 Republican candidates headed by a reality TV star kickstarted the process, the 2016 election cycle has been unique and unpredictable. With fewer than 80 days remaining, markets point to a one-sided contest yet both adjectives still apply.
Betfair punters will be used to the straight-up, binary choice available in the three US elections since our inception in 2001. This time around, as many as five candidates are garnering news coverage.
Whereas the Republican and Democrat nominees accounted for over 98% of the vote in 2004, 2008 and 2012, Hillary Clinton and Donald Trump are averaging only 88% combined in head-to-head polls. When Gary Johnson and Jill Stein are added to the question, that number shrinks to 79%.
In short, a fifth of the US electorate remains unattached to either Trump or Clinton, despite a lifetime in the media spotlight. The latest NBC poll showed Johnson and Stein on 16% combined, despite Americans knowing relatively nothing about them.
Considering both ran in 2012 and won less than 1%, this is a significant breakthrough, with the potential to grow. Were either to reach an average of 15%, they would get into the TV debates. Against two historically unpopular candidates, with the electorate more volatile than ever, that could have a gamechanging effect.
On 11% in that latest NBC poll, Johnson is more interesting. He is the former Republican Governor of New Mexico, now representing the Libertarian Party. A fervent free-marketeer and small-state advocate, Johnson's agenda appeals to many Republicans, whereas his social liberalism appeals to plenty of Democrats.
Libertarianism has a long history in US politics, with Ron Paul's insurgent campaign making waves in 2012, albeit under a Republican banner. Though most conservatives would never consider Johnson's social and foreign policies, some from the #NeverTrump movement regard themselves closer to him than nominee Trump - who has spent a lifetime supporting big government ideas and Democrats.
Representing the Green Party, Stein is chasing a smaller pool of voters, mostly on the Left. Clinton still hasn't sealed the deal with Bernie Sanders' supporters and yet more damaging e-mail revelations are likely to thwart any attempt to improve her terrible trustworthy ratings before November.
As odds of [280.0] imply, it would require a miracle for Johnson to become president, let alone [1000.0] chance Stein. Nevertheless, a surge would completely alter the electoral maths in most states, significantly lowering the winning target. No third party has won an electoral college vote since 1968 but Ross Perot had a profound influence when gaining 19% of the popular vote in 1992.
A minor candidate surge could ease Donald Trump's path to the presidency
Bill Clinton won that election with just 43% and his wife could follow suit. Equally, a third-party surge could open the door for Trump, without him needing to win over too many detractors. 60% of Americans have an unfavourable opinion of Trump but the other 40% have stayed loyal to the core through one PR crisis after another.
As it stands, supporters of these minor candidates effectively hold the balance of power in many swing states. Take the ultimate bellweather state of Ohio - an essential part of any route to Republican victory nowadays. Clinton's average lead there is 4%, whereas Johnson averages 9% and Stein 2.5%.
Therefore if Trump could somehow eat into Johnson's share, Clinton's advantage could disappear. Likewise any advance for Stein, whose left-wing supporters are surely likelier to break for Clinton, must be good news for Trump.
Evan McMullin could be the candidate that #NeverTrump have been waiting for
There is also a new name to consider - Evan McMullin. A former CIA operative and policy chief, McMullin is an anti-Trump Conservative with an unlikely plan to win the White House. He is a Mormon from Utah hoping to win that state and, theoretically hold the balance of power should neither Clinton or Trump gain a majority in the electoral college.
The latter scenario remains almost unimaginable but Utah - normally a Republican stronghold - could become interesting. Trump is toxic to the substantial Mormon community in Utah and elsewhere. McMullin will get on a few ballots and can win some of the conservatives that simply can't stomach any of the others.
Younger voters hold the key to any breakthrough
Of course these minor candidates could be swamped once the race cranks up after Labor Day. They will be unable to compete for cash, ads and building a ground game, let alone mainstream media coverage. If the race is regarded as close in a particular state, undecided voters will probably jump behind one of the potential presidents.
Nevertheless, this is certainly the best chance for a third party this century, reflecting two weak candidates but also wider trends within American society. Voters have never been less attached to the main parties or satisfied with a permanently gridlocked Congress. All three candidates reflect real, emerging political movements - libertarianism, environmentalism and anti-Trump conservatism.
Nor should we assume these voters are wedded to the mainstream choices like past electorates. Johnson and Stein are faring disproportionately well with younger voters, who are far less likely to identify with a party and far more likely to embrace libertarianism or green politics.
The resilience of their support and motivation of their voters could ultimately prove decisive. In what otherwise looks increasingly like a Clinton landslide, it maybe the likeliest potential gamechanger between now and November.
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