There is no bigger event in political betting than a US election - a multi-faceted marathon lasting nine months. Besides the main event in November, the most important single day is today.

Super Tuesday involves primary elections in 14 states plus two overseas territories, as party supporters vote to choose who will lead them at the General Election. In light of the Republican Party blocking challenges to Donald Trump, the Democrats have the primary stage all to themselves.

How the Race for the Nomination Works

Throughout the entire process, candidates are vying for a total of 3979 delegates, spread across the fifty states plus other territories or caucuses with a vote - American Samoa, Puerto Rico, Americans Abroad, for example. Votes won translate into 'pledged delegates' - meaning they are bound to support that candidate during the first round of voting at the party convention in July. If anyone wins a majority after that first round, they are the nominee.

Whilst the first four races all garnered a tremendous amount of airtime, and as always played a pivotal role, fewer than 4% of delegates have so far been allocated. Here's the current state of play.

BERNIE SANDERS        60
JOE BIDEN            53
PETE BUTTIGIEG        26
ELIZABETH WARREN    8
AMY KLOBUCHAR        7

These totals will change dramatically after Super Tuesday, when a further 1357 - 34.1% of the entire total - are in play. In addition to the main market - who will be the Democrat nominee - the race in each individual state is a betting market in its own right.

Regarding the main market, events are moving very fast. In the last 24 hours, Buttigieg and Klobuchar have withdrawn, setting up what the betting increasingly sees as a dual. Bernie Sanders is best priced at 2.1 (Bet365), while Joe Biden is a 2.5 chance (Hills).

The only others below 50/1 are Michael Bloomberg at 16/1 (Ladbrokes) - who has yet to appear on a ballot - and Hillary Clinton at 25/1 (PaddyPower). She isn’t even in the race and could only be the nominee following a bizarre and extremely unlikely process, were nobody to win a majority of delegates. 

The last two races were won decisively by the front-two - Sanders in Nevada, Biden in South Carolina. Bloomberg enters the fray today but the hype behind the billionaire’s candidacy is already fading.

It has all changed remarkably fast. A week ago, Biden was a 14/1 chance and not even favourite for SC. He then won the TV debate, the key endorsement of the state’s leading black politician and the primary by a 29% margin!

That decisive blow put paid to Buttigieg and Klobuchar’s chances and thus winnowed the opposition to Sanders. Both have now endorsed Biden. If Bloomberg fails on Super Tuesday, there’s a strong chance he will follow suit.

These moves reflect the burning question at the heart of this contest - Bernie or Not. Sanders is not a member of the Democrat Party (he usually votes with them, as an independent), and has an agenda considerably more radical than the above quartet. He has built a powerful social movement, attracting young voters and increasingly Hispanics to the polls.

However Sanders is toxic to a large percentage of Democrats. Many consider his policies too extreme, his supporters an abomination and his candidacy an enormous risk given a lifetime taking controversial stances. They note that Donald Trump is cheering for Sanders - presumably in expectation of beating him. 

Until today, this ‘anti-Sanders’ faction seemed ruinously split but these withdrawals have given Biden a relatively clear run. Warren and Bloomberg’s presence will confuse matters for now but a narrative is forming - a straight choice between a democratic socialist offering radical change or a moderate former Vice President offering a return to stability after the Trump years.

These recent developments mean we need to completely re-assess the polls for Super Tuesday states. We saw in South Carolina how primary voters often decide very late. The Biden surge played out beyond SC and now there are transfers from the withdrawn candidates to be won.
Sanders won’t win many transfers. Biden will and Warren might.

Bloomberg may underperform his polls. Strong early numbers in ST states were due to TV ads, rather than campaigning, and came largely at Biden’s expense. He’s since bombed in both debates and lost relevance as Biden has recovered. He may well fall below the 15% threshold to win delegates in most states. 

Big Upsets Are Relatively Common in Primaries

The 14 state races today are therefore now effectively duals too. Be very wary of betting at short odds-on in these - primaries can be very unpredictable. On this day four years ago, Donald Trump lost Alaska from odds around 1.03 and from not much bigger in Oklahoma. Later Sanders would defy odds of 34.0 in Michigan.

It would require an equivalent upset for Sanders to lose today’s most delegate-rich race, California, or Colorado - for which he’s a 1.04 chance. 

In the most exciting race of the night, Sanders is 1.73 (Corals) to win Texas. Those odds may reflect an assumption that his campaign will, as in Nevada, proved effective at mobilising new Latino voters.

Elsewhere in the South, I prefer Biden. North Carolina looks a sure thing at 1.27 (Ladbrokes). His odds have more than halved to win Arkansas 1.3 (PaddyPower) and Virginia 1.33 (Ladbrokes). 8/11 for Oklahoma (Corals) makes plenty of appeal. 

Where will all this leave us after Super Tuesday? Sanders looks set to retain the lead but not by a decisive margin or on course for a majority. Everything to play for, with many twists and turns ahead.