How might a Trump return impact global politics?

It is possible, of course, that Trump is exonerated in court and elected in November by a more conventional route. Either way, while Biden remains the current favourite, there is a plausible route back to the White House for the man he defeated in 2020.

Depending on the circumstances, this could have a profound impact on US politics. Given how divisive a figure Trump is, his re-election could spark serious internal fissures. But what might it mean for global politics?

While a new term would operate in a different domestic and global context to his first, Trump's previous time in office along with his statements since, offer a useful guide to possible areas of continuity and divergence with the current US leadership.

Climate change

One area that would likely shift considerably would be the US approach to climate change. During his first term, Trump expressed scepticism about climate change, reflected in his policies.

Soon after assuming office, in June 2017, Trump announced he would be withdrawing the US from the Paris Climate Accords agreed on by his predecessor Barack Obama. His justification was on economic grounds, arguing that the accords put the US at a "permanent disadvantage," compared to other countries.

When Biden assumed the presidency, he immediately re-joined the accords indicting a sharp dividing line between the two likely candidates in the 2024 election.

Since leaving office Trump has continued to downplay the threat of climate change. This includes comments that most climate scientists warn are woefully inaccurate. For example, in April Trump told Fox News, "When I listen to people talk about global warming, that the ocean will rise, in the next 300 years, by 1/8th of an inch…The environmentalists talk about all this nonsense."

Yet, CNN fact-checked these comments and concluded that his claims were, "not remotely close to accurate." In fact, sea levels are rising by 1/8th of an inch every year, not over 300 years.

Given such comments, it would be unsurprising if a newly-elected President Trump once again pulls out of the Paris Accords and pursues further policies that challenge the growing global consensus on climate change.

In fact, one powerful conservative lobby has urged him to do just that. The right-wing Washington think tank, The Heritage Foundation, recently published 'Project 2025,' an extensive programme for the first 180 days of an incoming Republican president.

Critics have argued it is a blueprint to dismantle US climate policy. Were Trump to be victorious in 2024, it is likely that the authors of this plan would have considerable influence.

China, Russia, and Ukraine

In contrast, Trump's approach to great power politics may not prove as different to Biden as some might expect.

On China, it should be recalled that it was Trump, not Biden, who initiated Washington's current stand-off with Beijing. As part of his 'America First' economic agenda, Trump levied tariffs on billions of dollars of goods from China, beginning a trade war.

This shattered the previous status quo that had dominated US thinking on China since the 1980s.

In the later stages of his presidency, US-China policy shifted from just trade to an all-of-government approach, including tougher domestic and international security postures, although Trump's own preference to pursue a trade deal with China at times undermined this.

In 2020 though, Trump's blunt rhetoric blaming China for the coronavirus pandemic, seemingly to deflect criticism of his own handling of the crisis, saw ties with Beijing sink to a new low.

Read more: Blinken visits China in attempt repair to rock-bottom relationship

While Biden's policies have been more consistent and less personal than Trump's, they have still followed the same rough focus and outline. China is now seen as a major threat to US interests. Relations with Beijing are unlikely to significantly shift if Trump returns to the Oval Office.

Relations with Russia, and Washington's approach to the war in Ukraine, however, look more likely to vary. Trump famously enjoyed good ties with Russian President Vladimir Putin and claimed at a rally in February that, "Putin never ever would have gone into Ukraine if I were president."

Biden has made defending Ukraine and supplying Kyiv with equipment and funds a central foreign policy goal. In contrast, Trump has suggested he might reverse this approach, endearing himself to a vocal portion of the Republican Party that favours ending support to Kyiv.

But Trump's favoured solution to the Ukraine crisis may not work as he hopes. Having stated that he would be able to end the war in 24 hours if elected, Trump told an interviewer in July that he would do this by bluffing both sides.

He stated, "I would tell Zelensky: No more. You got to make a deal. I would tell Putin: If you don't make a deal, we're going to give them a lot. We're going to give them more than they ever got if we have to. I will have the deal done in one day, one day."

However, Aaron Blake of the Washington Post has noted this is a flawed strategy. Now that both sides have seen Trump's supposed plan, they will know he is bluffing. It also underestimates the deep patriotic feelings on both sides that might mean Kyiv and Moscow continue to fight no matter what Washington's stance is.

Such an outcome would leave Trump with a dilemma: if his bluff fails, he must either continue to support Ukraine against some Republican wishes or pull funding and oversee what will be viewed as an American defeat.

Breaking with Biden's Ukraine policy may ultimately prove harder than he thinks.

The Middle East

The Middle East is another region of the world that might see more continuity than change under Trump.

Both he and Biden actually share many of the same goals. Each wants the US to step back from the region, protect key regional allies, and contain the threat from Iran. Yet each has pursued these differently, based on their different ideologies, personalities, and the global context in which they operated.

Trump aligned himself very closely with the governments of Israel and Saudi Arabia while pursuing an aggressive policy towards Iran, pulling out of the JCPOA agreed by Obama to limit Tehran's nuclear programme and imposing new sanctions.

Biden, in contrast, opted to revive the JCPOA, although negotiations remain ongoing. He was initially cold to both Israel and Saudi Arabia, though relations have since improved with both after he sought their support on the Ukraine war.

The major question would be over Iran. On his part, Israel's premier, Benjamin Netanyahu, would likely lobby for ending the revived JCPOA negotiations and renewed hostility to Tehran.

While the Gulf states absolutely do not want Iran to develop nuclear technology nor continue its interference in multiple Middle Eastern arenas, they may question whether hostility from Trump is the best way to achieve this.

With China now emerging as a viable broker between Tehran and Beijing's other Middle Eastern partners, some may question whether Trump's bullishness is still helpful.

In essence, the Middle East has moved on since Trump's first term and there may be less enthusiasm for his approach to the region than there was in 2017. Of course, this may not prove counter to Trump's own desires, given his preference for less involvement in the Middle East anyway.

Yet for all the likely continuity in current global policy priorities, a second Trump presidency carries with it the potential for unexpected ruptures.

In his first term Trump expressed his frustrations with Nato and his former National Security advisor turned critic, John Bolton, has suggested that, "in a second Trump term, we'd almost certainly withdraw from Nato."

Similarly, Trump showed disdain for European allies when he placed tariffs on EU steel, and some have suggested he might pursue a China-style trade war with the bloc were he to return to power.

Others, like Bruce Wolpe of the University of Sydney, have wondered if Trump's isolationist instincts would make him less willing to defend Taiwan from a Chinese attack.

Whether such dramatic outcomes occur is impossible to predict, not least given the particularly unpredictable nature of Donald Trump – what Bolton calls his, "erratic," nature. The return of this style would be a departure from the more calculable approach of Biden.

Domestic shifts

Yet as significant as these conscious changes to foreign policy might be, a far greater impact might come from changes that Trump makes at home.

Wolpe, writing in the Guardian, suggests a list of domestic moves Trump might make on returning to the presidency to secure his grip on power and punish those who challenged him.

These include declaring martial law, disobeying court orders, packing the Supreme Court, ignoring laws passed by Congress, detaining political enemies, shutting down media outlets and interfering in state elections.

While Wolpe might be exaggerating for effect, his point is that Trump showed in his first term that he was willing to play by different rules, and had no qualms about undermining US institutions and even, allegedly, its democratic processes.

There is no reason to suggest he would do things differently should he return to office. Irrespective of the potential impact at home, such moves would have a profound effect abroad, damaging US soft power.

Return of the unknown

In all likelihood, a lot of such speculation will prove misplaced. If Trump is able to overcome the significant obstacles in his path and somehow return to the White House his new administration will be limited in the number of changes it can make, even if it wishes to.

When he was elected in 2016 a lot of doom-laden predictions were made that turned out to be way off the mark of the reality that unfolded.

In certain major areas of foreign policy, like China, the Middle East and, to an extent, Ukraine, there is likely to be as much continuity as change given Trump's instincts and the global conditions he will be working in.

In contrast, areas like climate change policy might undergo major transformations. More significant though will be how domestic policy is impacted by Trump's return and what effect that has on perceptions of the US abroad.

Moreover, the return of Trump's erratic character to the White House would prompt allies and enemies to shift their calculations. One certainty is that US policy, for better or ill, would be far less predictable than under Biden.