All governments disappoint us in the end. Some policies fail, divisions open up, ideological dead-ends are reached and national problems are left unsolved. The big question is at what point widespread disillusion sets in: after a few months, a few years, or longer. The answer has decisive consequences for a government’s sense of itself and for its electoral fate. You might think this government, only seven weeks old, the first entirely new Labour administration for a quarter of a century, with a huge majority and ministers working hard while much of the country is on holiday, will be safe from voter disdain for quite a while. Yet that assumption may be optimistic. Not just because of Labour’s thin total vote at the election, or the immense national problems it has inherited, but for other, less examined reasons. Ruling from the centre-left is particularly difficult, as Labour governments have regularly demonstrated. And changes in the media and in how voters think have made that task even harder. Centre-left government, as its name suggests, is an awkward compromise: between a degree of leftwing radicalism and wherever ministers and their policy advisers and electoral strategists think the political middle ground is. Such governments typically try to find a balance between boosting capitalism and regulating it, between redistributing wealth and keeping economic elites content, between making foreign policy more ethical and accepting existing power arrangements. In theory, a government that both reforms and leaves things alone, according to “what works”, as Tony Blair put it during his long premiership, ought to appeal to a broad range of voters. As when he took office in 1997, today’s Britain is a country in deep difficulties and one where powerful interests, such as property owners, don’t want the status quo to be too upset. For his first half dozen years as premier, Blair used easy-to-justify reforms such as the introduction of a minimum wage and devolution for Scotland and Wales to persuade voters that Britain was being successfully modernised. Yet as soon as he tried to combine this mildly progressive project with more rightwing policies such as the privatisation of public services and participation in American wars, the credibility and coherence of his government were fatally damaged. For many people who stopped voting Labour, it was as if his earlier reforms had never happened. Too rightwing for some but too leftwing for others, he ended up pleasing fewer and fewer people, as the shrunken total Labour vote at his last election as prime minister in 2005 demonstrated – significantly lower than in even its 2019 defeat. The party has tried and failed to rescue his government’s reputation ever since. At last month’s election, Keir Starmer barely bettered Blair’s 2005 vote, and governments rarely gain in popularity. Starmer also faces a more impatient electorate than Blair did. Digital media have accelerated politics, including the speed with which new demands and expectations can spread. Meanwhile, over the past decade, many voters have also experienced a dramatic expansion of what politics can encompass: the 2014 Scottish independence campaign, Brexit, Corbynism, even the big, populist promises of Boris Johnson and Liz Truss. The centre-left can argue that these experiments all failed. But whether voters prefer what Starmer calls a politics that will “tread more lightly on your lives” is not yet clear. So far, Labour’s energetic start in office has not lifted the party’s poll ratings. The new administration has already done quite a few good things: settling public sector pay disputes, conducting diplomacy in more judicious language, getting rid of the Rwanda scheme and the Conservatives’ draconian “minimum service” anti-strike law. But the government has also repeatedly said it will have to make difficult choices – usually centre-left code for spending less money on the disadvantaged than they need or many Labour supporters would like. If Starmer’s premiership does produce the usual centre-left patchwork of enlightened policies, lost opportunities and reactionary measures, then Labour will need to find a way to make sense of and justify its mixed record: a clear, overarching government project or narrative. Simply not being the Conservatives will only get the party so far. As the election showed, the anti-Tory vote is fragmenting in unprecedented ways. Left-leaning Britons, too, will have to work out what they think about a Labour government, day by day and overall – not something they have had to do for at least 14 years. Successes, failures, omissions, betrayals: all will have to be weighed. Meanwhile the Green party, Plaid Cymru, the SNP, the growing number of independent MPs, and perhaps even the Liberal Democrats may well offer more radical alternatives. Some socialist thinkers have always believed that worthwhile centre-left government is impossible: a contradiction in terms. In his scathing, still relevant 1961 book Parliamentary Socialism, Ralph Miliband, father of the energy secretary Ed Miliband, dismissed the great bulk of Labour MPs as “bourgeois politicians with, at best, a certain bias towards social reform”. The working-class backgrounds of many new ministers may make the first part of that description seem out of date, but the rest of Miliband senior’s critique of Labour’s habitual caution in power will only be disproved by a major change in Starmer’s style of leadership. It could conceivably happen. Labour governments are rare, so looking at past examples to predict how a new one will act is less reliable than Labour-watchers like to make out. Our politics is also in a state of unusually intense flux. Starmer could take advantage of it to do centre-left government differently, by deferring less to the rich, creating a more expansive electoral coalition, being more inclusive of the poor and the young, and dropping some of centrism’s anxious assumptions about this country’s essential conservatism. Only a couple of years ago, almost no one imagined that by 2024 Labour would have more than three times as many Commons seats as the Tories. Supposedly, one of the key principles of centre-left politics is that governments should do what circumstances allow. This autumn, with the budget and the Labour conference, we will begin to find out whether the party likes having a great window of opportunity, or would prefer it to narrow again. Andy Beckett is a Guardian columnist