MOST Democrats, presumably, would like to hang on to the White House in 2016. Because convinced liberals are a minority of the American electorate, they will need to woo millions of centrists and swing voters to win the presidency. This being so, it is—to put it kindly—puzzling that so many Democrats want to fight the next election by marching angrily to Barack Obama’s left. Yet, logically, that is what Democratic activists and pundits mean when they urge Senator Elizabeth Warren, de facto leader of the party’s populist wing, to challenge Hillary Clinton for the presidential nomination.

There are a lot of Warren-admirers out there. Even more moderate sorts, who back Mrs Clinton but want her to adopt lots of Mrs Warren’s ideas and rhetoric, should be clear what that means. Mrs Warren stands for more redistribution than Mr Obama does. She would increase Social Security payments to the old and sick by collecting more tax from higher earners, and has clashed with the president over his (very modest) proposals to trim Social Security benefits by adjusting the cost-of-living rate to which they are pegged. Mrs Warren is also leading a Democratic revolt against Mr Obama’s foreign-trade agenda. On paper she is just a first-term senator from Massachusetts. But she has achieved clout far beyond her seniority, thanks to her rare talent for turning wonkish arguments into placard-ready slogans. Almost every Democratic senator joined her in a 24-hour rebellion against Mr Obama’s trade policy earlier this month, including several who normally support free trade. A frustrated Mr Obama says Mrs Warren is “absolutely wrong” about trade, arguing that America already imports lots from cheaper rivals, would like to nudge partners to open markets, and has a moment of leverage now to shape trading rules that suit all sides. Alas, Mrs Warren smells a conspiracy. She issued a 15-page report this week called “Broken Promises”, complaining that Mr Obama and previous presidents have not sued foreign governments often enough over their labour or environmental laws. At the same time she says existing trade pacts make it too easy for multinational corporations to sue America. It is sometimes hard to know what sort of trade pact could both please her and be acceptable to any foreign government. No matter. Fans cheer when she denounces deals that favour big business and “leave workers in the dirt”.

Such angry talk resonates. Mrs Warren received thunderous applause when she told the California Democratic Party convention on May 16th, “This country is not working for working people. It’s working only for those at the top. That’s not the American dream. That’s the American nightmare.”

To be fair, Mrs Warren is sincere in her moral indignation, and she came by it the hard way. Her Oklahoma childhood was stalked by financial ruin after her father fell ill. Her career as a scholar of bankruptcy law led her into the public arena, as a campaigner against predatory lenders. While still a Harvard professor she came to Washington to tangle with banks and their lobbyists over a new bankruptcy law then, after the credit crunch of 2008, over new regulations for Wall Street. She swiftly showed a knack for politics, as she cast complex financial regulations as homely and all-American. One early triumph saw her compare subprime mortgages to dangerous toasters: both can cost families their houses, she would say, and consumer-protection laws have long banned lethal kitchen appliances. When Republicans (egged on by banks that loathed her) blocked her ambitions to head a new agency protecting financial consumers, she ran successfully for the Senate in 2012.

That back-story helps explain Mrs Warren’s power. Like most Democrats, she thinks of federal regulation as a force for good, shielding regular folk from harm. But her own story has left her seething about the way Washington politics works most of the time. That combination puts her in a sweet spot with the grassroots left. She tells audiences that if they think the deck is stacked against the middle classes, they are right. “The game is rigged,” she likes to say, describing Wall Street CEOs and lobbyists strutting around Congress, bending the government to their will.

Warren fans think that such lines find support across America. They think voter disaffection is the most powerful force in modern politics, creating a natural majority for bold, radical policies to spread wealth and opportunity. They fret that Mrs Clinton, a rich woman with still richer friends, some of them on Wall Street, will fail to harness this populist moment. Mrs Warren sounds as if she agrees, telling Californian Democrats: “When we stand together, when we make it clear what we believe in, America is ready to stand with us.”

There are striking parallels with diehard conservatives. Senator Ted Cruz of Texas, a darling of the Tea Party right who is running for president, tells crowds that America is “fundamentally a centre-right country”, at least outside Washington, a place he calls “profoundly broken”. Republicans, Mr Cruz says, lose national elections when they choose moderate candidates who “don’t stand and draw a clear distinction, when [they] don’t stand for principle.”

Power without responsibility

Purists of left and right both face a similar problem: neither side has the numbers to win a presidential election without some crossover voters. But the left arguably has an extra problem. Mrs Warren’s message boils down to: Americans are right to be furious, Washington is run by special interests, government is broken and the economic pie is shrinking—and the solution lies in more Washington, and trusting government to distribute pie more fairly. How would she resolve that paradox? Nobody knows, because Mrs Warren—a shrewd politician—is not actually running for the presidency. Some time soon, her fans might like to stop and ask themselves why that might be.