America is facing unprecedented threats. The next president must make tough decisions

Every US presidential election for well over a century has been consequential – not just for that nation, but for the world. Sometimes it has been a matter of life and death for liberty, as when isolationism has been on the ballot at a time of global instability – such as in 1940.

John F Kennedy said that the choice in 1960 was whether the world would live half slave, half free, just as that very same choice for the United States had confronted voters in 1860 – and they’d chosen Abraham Lincoln.

Woodrow Wilson wanted the people to back a League of Nations to end wars; Franklin Roosevelt sought a mandate to rescue the economy “from fear itself”. Lyndon Johnson wanted to build “the great society”; Ronald Reagan to win the Cold War... less happily, George W Bush wanted to wage his “war on terror”.

None of these contests can be said to have been trivial, but some have been more epoch-making than others. The election of 2024 is one such choice.

It goes almost without saying that if Donald Trump does return to the White House, there will be grave consequences. There is always a certain complacency, in great civilised, pre-eminent nations, that their ways of life, systems of governance, and economic and military power are unassailable and beyond peril. That is the context of the present election – an assumption, such as those that once were made about the British empire or the Soviet Union, that the sun will not set on America.

Yet the dark shadows cast over the sanctity of the constitution by successive Trump candidacies have grown steadily more ominous and menacing. The rhetoric has been ramped up, the insults have intensified, the vengefulness has become ever more sinister. In a state of affairs that would have appalled previous generations, no one would be very surprised if a newly restored Donald Trump turned the resources of the state into a machine for retribution – and, abetted by a disgracefully compliant Supreme Court, sought to entrench his power unconditionally.

His reckless protectionism would fuel inflation, cost jobs and crash the dollar – with the Federal Reserve powerless to defend it. Domestically, America under Trump would be less free – and poorer.

Allowing Robert Kennedy Jr to “do what the hell he likes” with the health agencies – and permitting Elon Musk to experiment on the federal government – would be disastrous. Trump has, in the past, openly contemplated a second civil war in the US. He would easily be the worst president in history.

Frankly, Trump terrifies America’s friends – with good reason. His transactional approach to foreign affairs means that he cannot understand what every one of his predecessors since 1941 has grasped, which is that the US national interest is best served by Nato – whether the allies pay up or not.

He would abandon Ukraine to Vladimir Putin – and much else, too. He would deploy the same attitude to America’s friends and partners in east Asia and the Pacific – Japan, South Korea, Taiwan and Australia – mixing trade policy and national security in a lethal, self-destructive cocktail, to the delight of Xi Jinping. That mixture can be seen, too, in his latest policy towards Mexico and the southern border.

Trump says he wants to let Benjamin Netanyahu have a free hand in his various wars in the Middle East – putting war with Iran on the horizon. Under a Trump presidency, the United Nations and its agencies would be at best tolerated.

Virtually every nation in the world that holds the dollar as a reserve currency and trades with the US would be pushed towards recession by a Trump administration. Climate change, to Trump, is a “scam”, with all that entails for the long-term future of the planet.

Few would claim that Kamala Harris has all the answers to America’s challenges. The economic record of the Biden administration is a strong one, given the successive crises of the last few years, but much of it has been built on yet more debt. There is no Harris plan to get the borrowing down.

Sooner or later, the “exorbitant privilege” enjoyed by the dollar will be exhausted. Harris’s answer to inflation is to target supermarkets for alleged price-gouging, and there is no coherent strategy, behind her own brand of protectionism, to the challenge posed by China’s competitive advantage. It is China that has already emerged as the most potent rival to US hegemony – the only other economic, technological and military superpower on the planet in any position to overtake the Americans.

These are the fundamental factors that are driving America’s relative decline – and have created the context of industrial decay and diplomatic weakness that has made Americans turn inwards and against one another. These are the issues that the next president – and their successors – will need to find the answers to. That’s why elections matter.