“THE lesser of two evils is not an option. I won’t vote for evil.” So says Julie Edwards, a volunteer for the insurgent presidential campaign of Senator Bernie Sanders, explaining why she will spurn both main party candidates if—as looks almost certain—her hero loses the Democratic presidential primary and Hillary Clinton ends up battling Donald Trump. Ms Edwards was one of dozens of Sanders-backers gathered at an Indianapolis pub on May 3rd to watch the results of the Indiana presidential primary. Many, declaring themselves “Bernie or Bust” voters, pledged to write their hero’s name on to the ballot paper if he is not the Democratic nominee. Mrs Clinton is steeped in “incredibly horrendous scandals” and can never win a general election, averred Ms Edwards. Other volunteers called her “a criminal”, a “neocon” and—perhaps most damningly for some—a pragmatist.

A hard-bitten professional campaign consultant, hopping cross-country flights to snag rich donors, might find the crowd at the Union Jack Pub a little homespun. A bearded man startled babies by leading shouts of “Feel the Bern”, then, unbidden, apologised to a Native-American woman on behalf of his ancestors. But there was nothing woolly about the headlines that filled the pub’s TV screens, prompting whoops: they showed Mr Sanders beating Mrs Clinton in the Indiana primary, marking his 19th victory. More than 9m Americans have now voted for Mr Sanders (who does notably well among the young) and more than 2.4m have given him donations totalling $210m. Mrs Clinton remains well ahead, with more than 12m votes to date and an all-but-insurmountable lead in the race to accumulate delegates, as well as among the party bigwigs who cast ballots as superdelegates. Yet she is more respected than loved—helping to explain the startling success of Mr Sanders, a snowy-haired scold who thunders against global free-trade pacts, wants to break-up big banks and generally make America more like a Nordic social democracy.

Still, Mr Sanders’s power over the primary contest is fading. His fundraising dropped last month and his campaign recently laid off hundreds of staff. Even among true believers at the Union Jack Pub, many only hoped that he can still win. Attention is thus turning to how his clout will be felt from now on. While insisting that he still has a path to the nomination and will fight on for the last major prize, California’s state primary on June 7th, Mr Sanders has signalled his intent to exert power over Mrs Clinton as a nominee and president. Most directly, he wants to enshrine such policies as a $15-an hour minimum wage, a ban on natural-gas fracking and bank-bashing in the party platform approved at the Democratic National Convention.

Ben Wikler of MoveOn.org, a prominent campaign outfit of the left, suggests that Mr Sanders can still wield considerable sway by prodding Mrs Clinton to embrace progressive policies as a candidate, and even more sway when she fills big jobs in her government, citing the dictum “personnel is policy”. He credits the senator from Vermont with riding a “perfect populist storm”, at a moment when social media and digital tools have eroded the power of big media “gatekeepers” and big money donors—and when “the system has manifestly failed to deliver, for young people, for instance”.

But campaign platforms are soon forgotten and do not bring lasting change, cautions Howard Dean, the former governor of Vermont who staged his own insurgency in 2004. Mr Dean briefly led the presidential primary field with an internet-driven revolt against his own party, which he denounced for supporting George W. Bush’s tax cuts and invasion of Iraq. Mr Sanders is “not thinking clearly right now” says Mr Dean, adding: “I have been where he is, this is a very difficult time.” Admitting that victory is lost is not as hard as letting down supporters “energised” around the country, recalls the former candidate. Mr Dean, who later became a party boss as chairman of the Democratic National Committee and who is backing Mrs Clinton, is sceptical about another Sanders demand: to turn all Democratic presidential contests into primary elections open to independents and non-members. That would abolish the Iowa caucuses (the quirky, low-turnout gatherings that kick off each presidential season), and “I have been there and tried that,” says Mr Dean with a hollow laugh.

The revolution will be digitised

Have no doubt that the Sandernista movement is big: his rallies can draw tens of thousands, some reciting his best-known lines along with their hero. A harder question is: how big? Has the senator merely fired up the most liberal quarter of the electorate? Or has he (as Bernie fans insist, pointing to opinion polls) found causes that inspire nationwide majorities? Mr Dean, for one, suggests that his Vermont neighbour has correctly spotted issues that worry most Americans, starting with a sense that the economy is rigged, but has not found solutions with majority support.

Perhaps surprisingly, Mr Dean (now a silver-haired grandee, interviewed at his Washington law firm) and young volunteers at the Union Jack Pub agree on how Mr Sanders may wield lasting power: by changing the party from the bottom up, even though the Vermont senator joined the Democrats to run for the White House only after years as an independent. Mr Dean founded a group, Democracy for America, that claims to have elected 100 candidates from local councils to Congress. A Sanders-backed outfit could “easily raise $200m” and elect 1,000 candidates, predicts Mr Dean. That appeals to Elizabeth Hyde, a Sanders volunteer-leader in Indianapolis, who talks of a years-long campaign to move her party leftwards, copying “infiltration” tactics long used by the Republican right. In the short term, Ms Hyde is steeling herself to vote for Mrs Clinton if she must, to stop Mr Trump. She is not alone, polls suggest. The Sanders movement may well torment Democratic centrists for years to come. But sometimes elections precisely involve picking lesser evils.