SOMETIMES a single word can capture a moment in politics. In 2008 it was Hope that carried Barack Obama to the White House. A bleaker noun seems to hold voters in its power just now: Fight. The country’s combative mood helps to explain the huge crowds, some exceeding 28,000 people, that have been turning out to cheer Senator Bernie Sanders of Vermont, a pugnacious underdog in the contest for the next Democratic presidential nomination. Mr Sanders has risen in the polls all summer, closing fast on the front-runner, Hillary Clinton and even overtaking her in one August survey of New Hampshire voters.

It is not sunny optimism that explains this surge. A typical Sanders speech resembles a 90-minute sermon on modern America’s ills, delivered in the growling tones of his native Brooklyn. Hunched over a lectern, snowy hair aquiver with emotion, the 73-year-old’s usual targets include the “greed, recklessness and dishonesty” of Wall Street bankers, the malign influence of billionaire political donors, and the “abysmally low” wages that blight the lives of working families. Change will be hard, Mr Sanders warns audiences, and will require a “political revolution”. He is not joking (the senator rarely jokes). His proposals include moving towards a Canadian-style health system with publicly funded care for all, free tuition at public universities and a trillion-dollar infrastructure plan intended to create 13m jobs.

Mr Sanders’s supporters have been disappointed before. As one told the senator in Boone, Iowa on August 15th, in a sharp rebuke of Mr Obama: “I voted eight years ago for hope and change and I am still waiting.” By way of reassurance, Mr Sanders tells left-wing Democrats that he and they share a common loathing of the establishment, and a common willingness to engage it in combat. Though Mr Sanders has served in Washington since 1991, he sees himself as an outsider: a self-described democratic socialist from an ornery mountain state, who sits in Congress as an independent. His only executive experience was as mayor of Burlington in the 1980s, a city whose modest size did not preclude him from engaging in foreign policy—highlights included visits to the Soviet Union and a mayoral apology to Nicaragua for the policies of Ronald Reagan. Now Mr Sanders detects a chance in 2016 to lead a national uprising, drawing strength from the millions of working Americans who loathe mainstream politicians, news outlets and the economic status quo. Paraphrasing Franklin D. Roosevelt, he told the rally in Boone: “If the Koch brothers and the billionaire class hate my guts, I welcome their hatred.”

Sanders fans know that others struggle to see their hero in the White House, given the radical nature of his policies. But they point to new forces surging through American politics, and to the rise of non-traditional candidates, notably the property magnate Donald Trump, who leads the Republican presidential field.

Cornelia Flora, a retired sociology professor and one of the first Sanders activists in Iowa, senses a discontent that transcends left-right labels. She says the senator is “kind of like Trump, but he makes sense.” She calls Trump fans “silver-bullet thinkers”, looking for magical solutions like border walls to fix an American job crisis. In contrast, the professor suggests, organising for Mr Sanders will be a more “discursive” process, by which unhappy voters will be led to contemplate why the country is in its current state.

At Sanders headquarters, tucked away in a dowdy shopping centre on the edge of Des Moines, his Iowa campaign co-ordinator, Pete D’Alessandro, hails his boss as a “collective” populist looking to unite the oppressed, in contrast with those (the name Trump hovers, unspoken) who tell the poor to blame rival groups for their plight. Bernie-fans dream of awakening the more than one third of voting-age Americans who seldom cast ballots (even the presidential election of 2008, which set many records, saw just 64% turnout). Mr Sanders agrees, predicting that if he wins the Democratic nomination, he will inspire young and working Americans in a way that establishment politicians cannot.

Sanders Claus

But something old and problematic lurks beneath this vision of a new populism of the left. A central argument of the senator and his fans is that the poor have been voting against their own economic interests. They blame wicked billionaires and the corporate media for lulling the masses into this confusion. As the senator told supporters in Boone, they can help him by making working-class Republicans see that it is not in their interests to give tax breaks to the super-rich. “Our job is to educate and organise and when we do that, profound change will come,” Mr Sanders said. That mission to explain inspires Sandernistas, who are disproportionately white, well-educated and politically engaged.

Alas, there is nothing new about affluent lefties nagging angry voters to see that they are cross about the wrong things. And there is nothing new about these efforts causing offence. This is already happening. Activists from the Black Lives Matter movement have twice interrupted speeches by Mr Sanders to complain that he talks more about economic injustice than about racism, which they call the country’s most urgent crisis. Some Bernie-fans chided black activists to see that Mr Sanders is their ally: in return they found themselves dubbed “white supremacist liberals”.

Deep down, most people in Bernie-world are more pragmatic than might be supposed. At the rally in Boone and at a gathering for Democratic presidential candidates in Clear Lake, most Sanders supporters conceded, after much prodding, that their hero might not win the presidential nomination. As a result, they are glad that Mr Sanders has not launched explicit attacks on Mrs Clinton and her own armies of wealthy donors. She might not be their favoured champion—indeed a general lack of grassroots excitement towards Mrs Clinton is another reason why Sanders rallies are packed. But if she is their candidate in 2016, they want her fighting-fit.