Politics has brought so much angst in recent years that when hope comes along we should savour it. This week delivered a dollop of unexpectedly good news from the US, news that should encourage, and perhaps instruct, those who oppose the menace of nationalist populism the world over – even here in Britain.

True, the struggle against that danger has enjoyed mixed fortunes this autumn. Jair Bolsonaro was ejected in Brazil, only for an Israeli election to seal the comeback of Benjamin Netanyahu two days later. But the message from Tuesday’s US midterms is clear: populists can be defeated.

American voters had made that point two years ago, when they showed Donald Trump the door, but few thought they would do it again this time. The talk was of a Republican “red wave”, with both precedent and polls pointing to heavy losses for an incumbent Democratic party saddled with rising inflation and an unpopular president. This was not just a media invention: with only the odd exception, senior Democrats were braced for defeat. Instead, the party won several of the closest Senate races and kept losses in the House of Representatives so low that even if Republicans do take eventual control of that body – the votes are still being counted – it will not be with the emphatic majority they assumed.

It turns out that, even when Trump himself is not on the ballot, sufficient numbers of Americans will reject Trumpist candidates who have plunged deep into unhinged conspiracy theory and contempt for democracy, and they will defend their rights. There are lessons to learn here, for Democrats looking to 2024 most obviously, but also for those beyond the US battling their own versions of the Trumpist peril.

A first takeaway is that such an effort requires great discipline. The anti-Netanyahu forces in Israel lacked it: had several small opposition parties put aside their differences and formed alliances, they would have won enough seats to deprive the former PM of a governing majority. As it was, two of those parties narrowly failed to clear the electoral threshold to enter parliament, leaving Netanyahu smiling.

The Democrats were much more focused, exhibiting “an incredible amount of message discipline”, as the party strategist David Shor put it to me, sticking to those issues where the American public agree with them and avoiding those where they are out of step. They refused to be drawn on to the terrain where Republicans wanted to fight – even leftwing candidates distanced themselves from the “defund the police” slogan – digging in instead on turf where Democrats enjoy public support, whether that be jobs, healthcare or abortion rights. The latter issue was especially galvanising, following the supreme court’s summer decision to overturn Roe v Wade and its constitutional protection of a woman’s right to terminate a pregnancy.

But Democrats also made a case that some feared would bring no electoral reward. They pressed the argument that Trumpist Republicans posed a threat to democracy itself, reminding voters that this was the first election since the attempted insurrection of 6 January 2021, an event that too many Republicans excused and for which all but a handful refused to hold the former president accountable. Above all, Democrats cast as dangerously extreme the majority of Republicans who perpetuate Trump’s big lie that the election of 2020 was stolen.

Plenty of Democrats worried that was a mistake, fretting when Joe Biden made democracy the theme of his last major pre-election address. This, they warned, was too abstract an issue, of grave concern to liberal elites – to the university seminar rooms and opinion pages – but a luxury consideration for voters preoccupied with the cost of petrol. And yet the argument cut through. While those Republicans who had publicly resisted the big lie – Georgia’s governor, for example – won easily, Trumpist election-deniers fared especially badly, losing winnable contests in Pennsylvania, New Hampshire and Arizona. Moderate might be a dirty word to the Republican faithful, but extremist is a toxic label to the wider electorate. Strikingly, 56% of those American voters who describe themselves as moderate voted for Democrats.

There is encouragement here for anti-populists the world over. Of course, each context is different and few nations will have witnessed proof of the lethal danger posed by nationalist populism as vividly undeniable as the attempted coup of 6 January. Nevertheless, the Democrats’ experience suggests one can be too wary of issues lazily dismissed as of concern solely to a liberal elite.

In Britain, Labour has multiple reasons for steering clear of Brexit, but among the weakest is the notion that it’s of interest only to the “remoaner” chattering classes. Brexit is having an impact on people’s jobs, businesses, education, bills and basic freedom to move. In a way, it has more practical relevance to Britons’ daily lives than the question of democracy has to Americans’. And yet the opposition is shy of touching it. This week’s Democratic successes make a case for the abandonment of such timidity. The Democrats were brave, and it paid off.

There’s more advice contained in the US results. For any party of progress serious about winning, the support of women matters enormously: exit polls confirmed that abortion rights trailed just a few points behind inflation as the issue of greatest concern to voters and, as one analyst noted: “Abortion voters supported Democrats by a larger margin than inflation voters supported Republicans.” Unsurprisingly, those “abortion voters” included more women than men.

Young voters were crucial, too. While the over-45s favoured Republicans, the under-30s backed the Democrats by a staggering 28-point margin. Biden’s moves to shrink student debt deserve some credit for that. And, as always, minorities were an essential part of the Democratic coalition, though the drift rightward of Hispanic voters – most noticeably in Florida, where they helped Ron DeSantis win a landslide – is a warning to progressive parties everywhere that they cannot take the support of minority communities for granted. They have to earn it, demonstrating that they understand – and celebrate – the aspiration to move up and out as well as any conservative.

So no shortage of lessons from America. Of course, the differences between there and everywhere else are obvious and nothing reads across precisely. Except for one thing. What the US election proved once more is that the conventional wisdom is often wrong, that fatalism is always wrong – and that, every now and then, politics can turn out right.

• Jonathan Freedland is a Guardian columnist. Listen to his Politics Weekly America podcast here