AS A rule, populist insurgencies are rarely defeated with slogans in Latin. Yet there it was, swaying proudly over the protest march that filled the ceremonial heart of Washington, DC, a day after the inauguration of President Donald Trump—a handwritten sign reading: “Primum Non Nocere”. The cardboard sign, quoting the ancient medical principle “First, Do No Harm”, was held by Mike Gilbert, an epidemiologist from Boston, Massachusetts, who joined hundreds of thousands of others showing their disapproval of the new president. Mr Gilbert gave two reasons for attending what was officially the “Women’s March on Washington”, part of an internet-organised global protest that saw sister marches in hundreds of cities. He marched to show solidarity with “the women in my life” and to rally support for “sound science”, which he fears will be undermined by ideologues chosen to oversee scientific funding and regulation.

Many marchers set out to shame Mr Trump for boorishly boasting, years ago, that fame allowed him to grab women “by the pussy”. They wore knitted pink “pussy hats” with pointy ears, or carried such signs as “Viva La Vulva”. Some youngsters mocked the new president as a short-fingered nativist, chanting: “Can’t Build A Wall, Hands Too Small.” Still others said that they hoped their numbers would humiliate the president by dwarfing crowds that turned out for his inauguration. That gambit seemed to work, as Mr Trump spent his first days in office bragging implausibly about the size of his inaugural crowds.

Some leading Democrats enthuse that the moment is ripe for a Tea Party of the left (a “Herbal Tea Party”, some dub it), with a mission to resist the new president at every turn, challenging his legitimacy after he failed to win the popular vote. More thoughtful Democrats caution against reading too much into Hillary Clinton’s popular-vote advantage of 2.9m votes. Comparing raw-vote tallies in the 2016 and 2012 presidential elections, she did worse than Barack Obama in 34 states, notably in white, working-class and rural regions of 13 swing states that decided the election, while romping home in places that she was always going to win, such as California, New York and Massachusetts.

Republicans control 33 governors’ mansions and 32 state legislatures. Once a Supreme Court justice is confirmed, they will control, more or less, all three branches of the federal government. Democrats, in their deepest hole since the 1920s, need to work out how to win elections again. But before that they must agree on something more basic: whether they want to engage with voters who do not share their views on such issues as abortion or climate change, or are ready to write them off as a lost cause.

Some years ago David Wasserman, an analyst with the Cook Political Report, spotted a way to predict the political leanings of any given county: check whether it is home to a Whole Foods supermarket, purveyor of heirloom tomatoes and gluten-free dog biscuits to the Subaru-owning classes; or to a Cracker Barrel Old Country Store, a restaurant chain that offers chicken and dumplings and other comfort foods to mostly rural, often southern customers. Mr Trump won 76% of Cracker Barrel counties and 22% of Whole Foods counties, the Cook Political Report calculates. That 54 percentage-point gap is the widest ever: when George W. Bush was elected in 2000 it was 31 points. Eight years later when Barack Obama took office, it was 43.

Trump opponents must decide whether they can live with so wide a Whole Foods-Cracker Barrel gap. Alas, too many on the left and centre-left show little patience for the Americans who voted for Mr Trump—even for Trump voters who voted for Mr Obama at least once, of whom there are millions. On inauguration day in Washington, Lexington watched Trump supporters from out of town, some with school-age children, ride the Metro next to hipster-protesters with lapel badges reading: “Trump Has a Tiny Penis”. That was not the start of an exercise in persuasion. A day later lots of marchers said the priority should be coaxing out what they are sure is the country’s natural Democratic majority, ideally by embracing left-wing populism. There was much implicit scolding of Trump voters for being stupid, with posters bearing such messages as: “Make America Think Again”.

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Actually, Democrats need to become less thoughtless about Trump voters. For instance, many disapprove of such oil pipelines as Keystone XL, which Mr Trump has moved to revive by executive order. Democrats grumble about possible leaks, and prefer investing in renewable energy. That is their right. But a common Democratic talking point involves scoffing that pipeline-building generates only a few “temporary” jobs. As Representative Marc Veasey, a Democrat from Dallas-Fort Worth, said at a post-election meeting in Congress, he represents pipe-fitters and ironworkers whose careers are built on “temporary” jobs. Such folk think Democrats are not listening to them, he told colleagues.

Another Texas Democrat, Representative Beto O’Rourke, from the border city of El Paso, recalls that his party’s electoral strategy in 2016 revolved around trying to convince people that Mr Trump is “a bad guy”. However he cites Texan friends who agree with that description of Mr Trump, but still voted for him because they knew what he planned to do—build a border wall, bring back factory jobs—liked those plans, and could not say what Democrats wanted to achieve. Now Mr O’Rourke, an entrepreneur by background who is exploring a run in 2018 against Senator Ted Cruz, a doctrinaire Republican, worries that some colleagues are putting their faith in Tea Party-style obstructionism. But Democrats believe in making government work, he notes. Nor is he going to start making “tiny-hand jokes” about the president, he says: to mock the office is to show disrespect for his voters. To win an argument, Roman orators taught, first win the goodwill of your audience. That’s a Latin lesson with relevance.