Donald Trump, erstwhile 45th President of the United States, took the first step in what could be an improbable political comeback on the morning of Jan. 16 (Singapore time).

Trump secured a thumping victory in the Iowa Republican party caucus, the first major election of the Republican primaries, securing over 50 per cent of the vote in a field with multiple candidates.

His rivals for the Republican nomination, Florida governor Ron DeSantis and former South Carolina governor Nikki Haley, limped to a second and third place finish with 21 and 19 per cent of the vote respectively.

With the 2024 presidential election looming in November, here are four points of interest as we gear up for a long election year.

First up: What's a primary?

The two big political parties in the U.S. will go through a process of nominating their candidates for various offices, before the general election in November 2024.

These are called primaries, where many hopefuls compete to be elected as their party's candidate for a particular role.

Each U.S. state will hold a primary with a number of delegates as the prize. The candidate with the most delegates is (usually) acknowledged as the winner by the time the official nomination rolls around at the party's national convention, typically held in July.

If there's an incumbent, there's no need to hold a primary. Back in 2012, when Barack Obama was the sitting president, the Democratic party did not hold a primary. Mitt Romney won the Republican primary, before losing to Obama in the general election.

In 2016, when Obama could not run for president again, both the Democrats and Republicans held primaries to determine their presidential candidates, resulting in Hillary Clinton and Donald Trump.

But what's a caucus?

Different states have different ways of awarding their delegates. Some hold primary elections, which are run by the state.

Others have caucuses, which are run by the political parties themselves, not the state. Caucuses are technically considered political meetings, not elections.

During a caucus, a representative of a candidate will make a speech about why the party should choose them, and then the attendees (or caucusgoers) vote by secret ballot.

Whether it's a primary election or a caucus, the delegates are allocated based on the percentage of the vote received by each candidate. So you can finish in third place and still earn delegates.

Now that you're up to speed, here's the fallout from Iowa.

1. It will be Trump vs Biden

Barring a fatal incident of some kind, the 2024 election will be a rematch of 2020.

Despite a few no-hopers fantasising that they can replace Joe Biden as the Democratic nominee, like Representative Dean Phillips and Robert Kennedy Jr., Biden will be the nominee.

No sitting president has ever been denied a nomination for a second term if they wanted one since 1856, when Franklin Pierce was removed as the Democratic party candidate.

There have been strong challenges in the past (recall Ronald Reagan challenging Gerald Ford in 1976, or Eugene McCarthy challenging Lyndon Johnson in 1968), but those failed to unseat the incumbent.

Interestingly enough, strong primary challenges usually result in the challenged president losing the general election (Ford lost to Jimmy Carter in 1976, Johnson stepped down and the party's eventual candidate, Hubert Humphrey, lost to Richard Nixon in 1968).

Trump is inevitable

With Biden assured as the Dem nominee, the scale of Trump's win is big enough to settle any lingering doubts over the Republican primary.

Winning by 30 points, a party record, Trump did very well with rural and working-class voters.

According to The New York Times, he also won big with white evangelical Christian voters and those who describe themselves as "very conservative" — in other words, the backbone of the Republican party.

Trump's victory is all the more remarkable given that he didn't do as much campaigning in Iowa as opposed to his rivals. Trump skipped the party debate and did not secure the endorsement of the influential Iowa governor, Kim Reynolds.

Trump remains a lock for the nomination, barring unforeseen circumstances.

2. Nikki Haley, not Ron DeSantis, will be Trump's main challenger

It may seem counterintuitive, given that DeSantis finished second while Haley finished third.

However, one should consider the narrow margin of DeSantis' lead — he only did two points better than Haley.

And this was after DeSantis mounted one of the most extensive campaigns in Iowa primary history, visiting all 99 counties in the state, showing up for all the debates and sinking US$30 million (S$40.3 million) into radio, TV and digital ads.

Iowa was also considered one of the primary states that was "friendliest" to DeSantis, with his numbers not looking as good in New Hampshire, the next primary state.

Meanwhile, Haley put in a much better than expected performance.

She even won a single county to deny Trump sweeping all 99, almost unbelievably, by just one vote.

And by a margin of 1 vote Nikki Haley appears to have won Johnson County (Iowa City), leaving Donald Trump that close to a 99-county sweep: pic.twitter.com/MI5bearyPx

— Steve Kornacki (@SteveKornacki) January 16, 2024

Haley can now take her strong third-place finish to New Hampshire, where polls have indicated she will do better than in Iowa.

3. Vivek Ramaswamy flamed out

Another young challenger caught the eye for his splashy presentation and provocative statements, the under-40 tech millionaire Vivek Ramaswamy.

Although Trump wasn't present for debates, Vivek almost seemed like a personal representative in his stead. He clung tightly to Trump's policies and persona, declaring that if elected, he would give Trump a full presidential pardon "on day one".

However, his outlandish statements attracted controversy, calling Haley a "fascist" and promising to end birthright citizenship in the U.S. In return, Vivek was often the target of attacks from the other candidates during debates.

Nikki Haley to Vivek Ramaswamy: “Honestly, every time I hear you, I feel a little bit dumber…” pic.twitter.com/NX3eDJl76O

— The Recount (@therecount) September 28, 2023

For his unwavering loyalty, Vivek was rewarded with Trump blasting him as a "fraud" and "not MAGA".

Vivek came up against the inevitable reality that being a substitute Trump is no good as long as Trump remains on the ballot.

He suspended his campaign and endorsed (who else) Trump.

4. Things could change if there's a conviction

Does this mean Trump will be the 45th and 47th President of the United States? Not so fast.

There's still the matter of Trump's pending criminal cases. The New Yorker is mired in a swamp of legal troubles, including charges for illegally retaining classified documents, attempting to overturn the result of the 2020 election, defamation linked to a previous sexual abuse trial and attempting to overturn the result of the 2020 election (in Georgia specifically).

While Trump's approval ratings remain high, that could change if he is convicted in any one of his criminal trials before the November election.

Preliminary entrance poll data here out of Iowa — this seems significant pic.twitter.com/CT29Lsup54

— G Elliott Morris (@gelliottmorris) January 16, 2024

And that would change the race entirely.

Top image from Donald Trump's Facebook page.