It’s been a long time since anyone achieved what Donald Trump is trying to do in 2024. In fact, a former US president has only once successfully sought re-election – back in 1892, when anti-corruption crusader Grover Cleveland beat incumbent Benjamin Harrison, a great-grandson of one of the country’s “founding fathers”.

Not only for that reason does this year’s US presidential campaign promise to be one for the ages. It’s also likely to end up as the first duel between two presidents – one former, the other incumbent – since William Howard Taft and former president Theodore Roosevelt both lost to Woodrow Wilson in 1912. (Herbert Hoover tried it on in 1940 but failed to win the Republican nomination.)

And while Joe Biden is all but assured of his party’s support for a second term – setting a record for the oldest-ever US president if he wins, aged 81 – the Republicans may be in for a wild ride. Trump has already disposed of all but one of his major rivals, after Florida governor Ron DeSantis dropped out of the race on January 21. But hanging over Trump is a decision pending from the US Supreme Court that may see him ruled ineligible from running at all. An even weirder, albeit unlikely twist: given the raft of criminal charges Trump faces, he could plausibly win the nomination and the presidency and have to serve his term from the inside of a jail cell.

What is a primary, anyway? Why is the process, which lasts some seven months, so convoluted, confusing and downright quirky?

How do the primaries work?

“Many things about America can be understood as the downstream consequence of a really peculiar presidential nominating system,” says Zim Nwokora, a senior lecturer in politics and policy studies at Deakin University. “To my mind, it’s absolutely at the heart of why American politics works as it does.”

There is surprisingly little in the US Constitution that speaks to how candidates should be chosen – so exactly how the process runs each year can be a bit of a moveable feast. Until the 1970s, party bosses in smoky back rooms held much of the sway. “They sometimes had primaries but they were no more than illustrative,” says Nwokora. “They gave the elites information about how the people in their state thought but they weren’t binding in any meaningful sense.”

That largely changed after the chaotic Democratic National Convention of 1968, which saw police clash with protesters including students opposing the Vietnam War. Hubert Humphrey was chosen as the party’s presidential candidate despite not having won a single primary contest (and went on to lose the general election, to Richard Nixon). After the Democrats reviewed the process, much more power flowed to the rank and file and the Republicans subsequently followed suit, albeit in their own way.

‘You’ve got people who are willing to take an hour to two hours on a really cold Monday night and try to convince their neighbours and people in their community to support their candidate.’

Thomas Adams, University of South Alabama

To best understand the primaries it’s easiest to begin at the end – when both the Democrats and Republicans officially nominate their presidential candidates. This occurs every four years at vast national conventions, where thousands of party faithful called delegates – plucked from the ranks of local party members, loyal campaign workers and the like – gather to vote for their preferred candidate. This year, the Republicans will hold their convention from July 15 to 18 at a basketball arena in Milwaukee, Wisconsin; the Democrats from August 19 to 22 in another arena in Chicago, Illinois.

Delegates are divided into two main groups: most are “pledged” or “bound” to represent the wishes of voters from their party in their home state, the rest are not (they can vote for whoever they choose at the convention). There are some 157 unpledged – or unbound – delegates for the Republicans and 730 for the Democrats, including former presidents. These folk, however, only really play a role at the convention if the race is still too close to call and their votes can make a difference.

Of pledged delegates, there are 3936 for the Democrats, 2272 for the Republicans. The states all have varying numbers of these delegates, based on population: Nevada, for example, has just 36 Democrat-bound pledged delegates while California (on March 5, Super Tuesday) has a bountiful 424 up for grabs. And within the framework of national party rules, each state has its own – slightly varying – methods to determine how many of their parties’ raft of delegates will ultimately support each candidate at the convention, finally determining – at last – who will represent their party in the presidential election.

This is where the primaries come in: statewide elections held either as conventional ballots run by state authorities, or the less common caucuses, run by the parties themselves, where party members gather in places such as school halls to argue about which candidate they should support, sometimes voting with a show of hands.

Caucusing remains “an interesting process”, says Thomas Adams, a professor at the University of South Alabama who also teaches at the University of Sydney. “You’ve got people who are willing to take an hour to two hours on a really cold Monday night and come out and spend some time and try to convince their neighbours and their friends and people in their community to support their candidate.”

But most of the ballots take place in primaries, which vary slightly state to state in how voting works. In some states’ primaries you can largely vote for the candidate you want, irrespective of your party allegiance. In others, you must be a registered party member and can take only that party’s ballot paper. And while some states allow early mail-in votes, some require an in-person appearance. The Democrats allocate candidates a number of delegates that corresponds to their proportion of the vote. The Republicans can use a mix of proportional allocation and winner-takes-all, which can accelerate a leading candidate beyond reach of their rivals.

Either way, your vote determines how many delegates the surviving candidates will eventually be awarded going into the national conventions. New Hamp­shire, for one, holds an “open” primary, mean­ing both registered party members and non-aligned voters can par­ti­cip­ate in the same ballot.

Some states, meanwhile, hold both parties’ caucuses or primaries on the same day, such as New Hampshire, and some don’t. Some choose to run the ballot on the same date as other states (such as the 16 who converge on Super Tuesday on March 5). But many don’t do either, necessitating a drawn-out affair that demands the candidates campaign in as many of the 50 states as they can, flying in and out for personal appearances, followed by fleets of buses and their apparatchiks amid a blitz of advertising. (US territories such as the Virgin Islands, Guam and the Northern Mariana Islands also play a role but cough up only a handful of delegates.)

Ron DeSantis visited every one of that state’s 99 counties (and won none, prompting him to quit before the New Hampshire primary).

It can be exhausting and extremely expensive – two factors that usually lead to most candidates withdrawing long before the primaries are complete. NPR estimated that by mid-January the Republican candidates alone had already spent some $450 million in advertising. Former South Carolina governor Nikki Haley recently announced she will spend $6 million on advertising just in her home state of South Carolina.

Look at it as survival of the fittest, says Deakin University’s Zim Nwokora. “Putting them through the gauntlet is probably quite a good way of seeing what they’re made of,” he says. “It’s a really gruelling race that goes on for months and months where they have to appeal to many different groups of people, having to shape-shift depending on where they are in the country. The candidates who can get through that are normally pretty hardy.”

A typical day on the trail: Haley, campaigning in New Hampshire, started one morning in the city of Hollis meeting with voters then scooted nearly 40 kilometres to Manchester (an average minus 12 degrees at this time of year) for an appearance with the state’s Republican governor before ending the day with a CNN town hall meeting in Henniker from 9pm. In Iowa, Republican Ron DeSantis visited every one of that state’s 99 counties (and won none, prompting him to quit before the New Hampshire primary). Donald Trump visited Iowa only “about a dozen times”, reported The New York Times, which still seems a lot.

It’s a much smoother road for Joe Biden, who is all but assured his party’s nomination. No sitting president has lost a primary nomination in modern US history. For Biden, the primaries are about setting his party’s agenda and already campaigning for the presidency. His opponents, Marianne Williamson, a self-help author and former spiritual adviser to Oprah Winfrey, and Minnesotan Dean Phillips, are most likely running to raise their personal profiles or have plans for a future tilt at the presidency.

Why is Iowa such a big deal?

Iowa is first cab off the rank, and has been since 1972, when it hosted that year’s Democratic caucus (the Republicans followed four years later). Despite delivering only a handful of delegates (40 Republican, 46 Democrat), it receives outsized attention from candidates and media alike, reflecting the role that tradition, custom and pageantry exert on US politics. Which is why contender Ron DeSantis basically went all-in on Iowa with his campaign effort, only to land a distant second to Trump and bowing out.

Even early in the process, it’s all about the money, says Bruce Wolpe, a Colorado native and a senior fellow at the United States Study Centre at the University of Sydney. “DeSantis attracted backers with tens of millions of dollars but what do they have to show for it? Nothing.”

If you win in Iowa it’s supposed to be a good omen for the rest of the campaign. This is partially true: the-then little-known former governor Jimmy Carter went on to become president after winning Iowa in 1976. Yet Trump also won Iowa in 2020 (virtually unopposed as befitted an incumbent president) and lost the presidency. And the three Iowa primaries before that were just as unlucky for Republican winners: Ted Cruz (2016), abortion-opposing Rick Santorum (2012) and Mike Huckabee (2008) all triumphed in the potato state yet failed to ultimately capture their party’s nomination. In contrast, Joe Biden came a miserable fourth in Iowa in 2020 for the Democrats but went on to win the highest office in the land after coming back strongly in later states; Bill Clinton did the same after he also lost Iowa in 1992.

Nevertheless, Iowa clearly exerts some kind of voodoo. Biden made sure he wouldn’t have a poor showing in Iowa this time by going so far as to change his party’s rules to delay the result, which would likely be a shoo-in anyway. (Instead of a one-day caucus, Democrats have mailed in what they call an “expression of presidential preference”, the results of which will not be made public until March 5, buried amid the rest of the Super Tuesday returns.)

But why is it always Iowa that starts the campaign rolling? First, it is state law. Second, Iowa employs a particularly complicated process requiring the parties to hold multiple conventions before the delegate count is decided. This takes months. (When you read that Donald Trump received 20 delegates at the Iowa caucuses, that’s currently still an estimate.)

“That is such a dog’s breakfast that the media never report it,” says John Hart, a former head of department at ANU and author of The Presidential Branch: From Washington to Clinton. “They just assume that the results from the Iowa precinct caucuses will be reflected all the way through and the candidates will get the number of delegates at the national convention that they got in the precinct caucuses.

“The problem is, of course, that some of those candidates won’t be in the race when the Republicans hold their convention in July.”

What’s so unusual about New Hampshire (and Nevada)?

The first primary (remember, Iowa is a caucus), New Hampshire is of vital importance to the Republicans, who are now running a two-way contest between Trump and Nikki Haley, although DeSantis’ (admittedly slightly grudging) public support for Trump following his withdrawal could prove to be another curveball. As the first contest after Iowa, it will either keep Haley in the race – and, critically, encourage her donors to stay the course – or cement Trump as the nominee-in-waiting.

At least one of Haley’s billionaire financial backers is hanging on the result, according to the Financial Times, which reported that Ken Lan­gone, co-founder of US retail chain Home Depot, said he was pre­pared to give Haley “a nice sum of money” but “[i]f she doesn’t get trac­tion in New Hamp­shire, you don’t throw money down a rat hole.”

For the Democrats, New Hampshire is proving curly thanks to an internal party battle over the timing of the primary, which was only partly resolved. The national Democrats wanted it moved to later in the year so South Carolina – a more racially and economically diverse state that better represents the party’s support base – could host the first actual primary. But that would have required a change to New Hampshire legislation, which mandates it has to hold its primary before any other.

The result: the Democratic primary is going ahead on January 23, alongside the Republican primary, but it won’t count for much. Biden has dropped off the ballot and the party has punished the state branch by slashing the number of delegates it will send to the national conference in July. The intention is to give the impression that South Carolina is where the Democratic roadshow will really get underway.

It’s Nevada, in February, where it gets truly weird for the Republicans. Traditionally, their party has held caucuses there but following the 2020 presidential campaign the state government legislated to mandate that state’s contest a primary if at least one candidate wanted it.

One theory is Haley hopes a solid win in the dead-rubber primary will still boost her profile and renew her momentum going into her home state of South Carolina.

Broad brush: the Republicans pledged to hold a caucus anyway, and said that only the caucus result would be taken into account when allocating delegates (which the courts upheld). To further direct its candidates into the caucus, the state branch also dictated that any candidate who did still enter the primary (on February 6) would be ruled ineligible to also run in the caucus two days later.

So it was somewhat baffling when Nikki Haley went ahead and entered the primary anyway, since that means she is now guaranteed exactly zero of Nevada’s 26 Republican pledged delegates. Donald Trump, running in the caucus, will hoover up virtually all of them with DeSantis gone. Why did Haley choose the primary? She’s not saying. One theory is that she hopes a solid win in the dead-rubber contest will boost her profile and renew her momentum going into her home state of South Carolina on February 24, where there are 50 Republican delegates up for grabs.

How likely is it Trump will be ruled ineligible to stand?

So to Colorado, whose primary is on March 5 (Super Tuesday) and where that state’s Supreme Court has ruled that Trump is ineligible to stand due to charges of insurrection.

The Colorado case hinged on three key questions. First, whether it was an insurrection when Trump supporters stormed the Capitol (the seat of Congress) in Washington, DC, on January 6, 2021, following a rally at which Trump repeated false claims that the election held in November 2021 had been fraudulently stolen from him.

Second, whether Trump had engaged in that insurrection through his messages to supporters and his Twitter posts.

Third, and crucially, whether Section 3 of the 14th Amendment, adopted after the US Civil War and rarely mentioned since, specifically applied to the presidency.

The court in Colorado answered yes to all three and barred Trump from that state’s ballot. However, it stayed its decision to allow the national Supreme Court to hear Trump’s appeal, allowing Trump to still appear on the ballot until a decision was made. Indeed, his name will have already been printed on the ballot papers, which are mailed to military and overseas voters weeks ahead of the poll.

The US Supreme Court will hear oral arguments on February 8 and begin deliberating the next day. It appears line-ball there will be a decision before the March 5 ballot. For the Colorado judgment to stand, the superior court will need to agree that it ruled correctly on every aspect of the case; in other words, if it disagrees with any part then the decision will be overturned.

‘I don’t think the Republican Party will be stupid enough to nominate Trump as a candidate if they know he’s barred from becoming president.’

John Hart, author of The Presidential Branch: From Washington to Clinton.

If, however, the US Supreme Court upholds Colorado, one part would be straightforward, says Hart: “When those Republican Colorado delegates get to the National Republican Convention, they won’t be able to give their votes to Trump because he’ll be disqualified if the Colorado decision is upheld.”

Maine would then come into play too: like Colorado, it has barred Trump from the ballot but stayed its decision pending the US Supreme Court ruling.

Nationally, not everyone is clear about what would happen next. The Seattle Times believes a decision upholding Colorado would automatically bar Trump from the presidency. The New York Times, on January 5, was more circumspect, only allowing that “the sweep of the court’s ruling is likely to be broad” and “will most likely also determine his eligibility to run in the general election and to hold office at all”.

Hart believes that because the decision concerns the Constitution it would have to apply nationally. And then what? “How would that affect the nomination contest and the election? Well, there’s no precedent for that,” he says. “Although I don’t think the Republican Party will be stupid enough to nominate Trump as a candidate if they know he’s barred from becoming president.”

He also notes: “The Supreme Court opinion can’t be appealed. The only way it could be overruled is a clause in Section 3 of the 14th Amendment – which says you can’t hold public office if you have committed insurrection – that allows Congress to override the clause with a two-thirds vote in both houses.” Which would never happen with a Democrat-controlled Senate.

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Then there’s the other problem. Trump has been criminally indicted in four separate cases with multiple felony charges. If convicted, he could be sent to prison. Would that prevent him from becoming president? Not at all. Such an outcome would put him in the company of Eugene Debs, imprisoned as a “radical” and who unsuccessfully ran for president from jail in 1920 and conspiracy theorist Lyndon LaRouche who in 1992, while serving a 15-year sentence for mail fraud and campaign fraud conspiracy, somehow still managed to receive over 26,000 votes.

The Constitution lists only three qualifications for the presidency. The president must be at least 35 years of age, be a natural-born citizen (someone who was a US citizen at birth and did not need to be naturalised later in life) and must have lived in the US for at least 14 years. Trump meets these criteria. Should he win the presidency, he could hold office behind bars or pardon himself. As John Hart says, this has all “the makings of a good novel”.

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