Until last week’s Chesham and Amersham byelection, politics seemed incredibly easy for Boris Johnson’s Conservatives. However disastrously they governed, the political outcomes – in opinion polls, elections, and control of the national conversation – were consistently favourable. Johnson has arguably been Britain’s most dominant incompetent ever. In our often-sour old democracy, politics is supposed to be difficult, especially for parties in their second decade in office, when disillusionment has usually set in. But the government has seemingly defied this convention, as it has so many others. One of the keys to its unlikely ascendancy has been a willingness to pick fights. Liberals, lefties, lawyers, remainers, antiracists, Scottish nationalists, the EU, Channel 4, the BBC, even the Oxford students who voted to take down a photo of the Queen – no potential enemy has been too large or too small, it seems, for the government to leave it in peace. You could say there has been a frankness about this appetite for confrontation. In some ways politics is always about conflict, between interest groups and philosophies as well as parties. Before Johnson, prime ministers such as Tony Blair and David Cameron often sought to play these conflicts down – “We’re all in this together,” as Cameron liked to say – in order to appeal as widely as possible. Yet since 2015 the Conservatives have found that they can win elections with the strong support of only a few large sections of the population, principally older white voters and inhabitants of rural and smalltown England. Out of this realisation the Johnson government’s strategy of confrontation has emerged. Overseen by his trusted adviser Munira Mirza – a former member of the abrasive but surprisingly rightwing Revolutionary Communist party, who is now head of the Downing Street policy unit – this strategy claims that the best way to mobilise these groups of sometimes anxious and resentful voters is to tell them that their country and values are being undermined by subversive forces. As a government source recently told the website Tortoise: “Boris thinks that he and Munira are in the same place on this as the vast majority of the public, and that every time there is another row about statues or Churchill or white privilege, another Labour seat becomes winnable.” If the Conservatives capture the west Yorkshire seat of Batley and Spen from Labour next week, as is widely expected, then the Tory culture warriors will feel further vindicated. Their aggression seems to bewilder what remains of centrist Britain. From the Tory remainers who lost their seats in the 2019 election to Keir Starmer, with his ineffectual “constructive opposition”, our politics is strewn with reasonable people who haven’t come to terms yet with its change of tone. The media have been much happier. Confrontational ministers attract audiences, from Twitter to the Today programme. Meanwhile the rightwing press, which has been picking fights with liberals and lefties for decades, seems delighted to see the Conservatives so wholeheartedly joining in. In their coordination of attack lines, the relationship between the party and these newspapers feels as close as it has ever been. This aggression also seems to suit the times. Ever since the 2008 financial crisis, much of our politics has been a search for scapegoats, for people to blame for the ending of the relative prosperity and stability of the 90s and 2000s. Attacking the liberal left is a good way of drawing attention away from the real causes of today’s deep environmental and economic crises: Conservative free-market capitalism and the consumer appetites of voters themselves. And yet there is something a bit too neat and self-satisfied about this Tory strategy. There are no magic potions in politics: the effects of new tactics always wear off after a while. The unexpected loss of the Tory citadel of Chesham and Amersham to the Lib Dems may be a sign that aggression is starting to repel. Voters there preferred Sarah Green, a remainer who emphasised her record of “helping individuals facing injustice”. After years of polarised, exhausting politics, it would not be a surprise if voters elsewhere also began to find less divisive figures appealing again. The relatively consensual politics of the 90s and 00s was itself partly a reaction against the red-toothed Conservatism of the Thatcher era, with its constant hunger for “the enemy within”. At the G7 in Cornwall this month, there was another sign that Tory aggression may be reaching its useful limits. Johnson’s plans to use the gathering as an advertisement for “Global Britain” were partly ruined by his government’s argument with the EU over Northern Ireland. Like all rows between Britain and the EU, this may play well with Tory voters. But to see it in only those terms is shortsighted and parochial. Not all politics is national; relations with other countries also matter. If Britain is seen as untrustworthy in trade negotiations, that will affect the economy and ultimately voters’ incomes. Blair sometimes made the mistake as premier of trying to reduce politics to the governmental, to efficient administration. Johnson is making a different but equally large error: trying to reduce politics to the electoral. And as he may discover if the post-Brexit trade deals he promised don’t happen, elections can be influenced by external factors. Culture wars and government flag-waving may attract new voters, but they may melt away if a clumsily nationalistic foreign policy makes it harder for them to pay their bills. By picking fights, the Conservatives also assume that their chosen enemies are weak and will remain so. Yet the balance of forces in a society isn’t static. Today’s left-leaning millenials, so derided by the Tories, will become decisive voters in future elections, like generations of young people before them. Unless they drastically change their views, it’s hard to see what Conservatism can offer them. Finally, all the current, outwardly-directed Tory aggression feels like a premonition of – or a way of delaying – the battles likely to come within Conservatism itself: between its northern and southern voters, its free-spending ministers and fiscally cautious ones, its free-marketeers and economic interventionists, its reactionaries and social liberals. In Chesham and Amersham, some of these tensions burst into the open, and the Tory vote disintegrated. Divisive politics, when it’s successful, is about drawing lines: between your party and an electorally sufficient mass of supporters, on the one side, and your enemies on the other. Johnson’s government is doing that well for now. But if lines start being drawn within your own party, politics gets harder. When that happens – and the Tories’ acrimonious history since Thatcher suggests it soon will – Johnson’s days of easy dominance will feel like a distant world. Andy Beckett is a Guardian columnist