Chalk up another loss for conventional wisdom. As Thursday dawned in Great Britain, it was expected that Prime Minister Theresa May’s Conservative Party would expand its majority in Parliament over the Labour Party and its “far-left” leader Jeremy Corbyn. Friday dawned upon a different reality: The Conservatives have 318 seats — a loss of 13 seats from the previous election and eight short of the 326 needed an official majority. They will form a coalition government with the far-right Democratic Unionist Party, but with fewer votes to spare for any vote on Brexit (or any vote at all) the new government will be far weaker and less stable. May’s resignation and/or another election soon are both distinct possibilities.

Corbyn and Labour, with 262 seats, on the other hand have beaten every expectation: the most seats for Labour since 2005, the biggest share of the popular vote since 2001 and the largest popular vote swing toward Labour (almost 10 percent) since 1945. Corbyn’s success provides a model for U.S. progressives in 2018, 2020 and beyond: If you need turnout to win — as liberals in the United States do — you need a bold, uncompromising platform with real solutions

Look at what Corbyn succeeded in spite of. He was attacked mercilessly by other Labour members of Parliament and party leaders, including former prime minister Tony Blair. (Many of the Labour MPs who held their seats on Thursday had voted “no confidence” in him just last year.) He faced an unprecedentedly hostile media environment — not just the standard mudslinging from right-wing tabloids, but skepticism and condescension from “objective” and even ostensibly pro-Labour outlets. Even many loyal supporters worried when the election began that he would set back leftism.

Then look at what drove Corbyn to victory. No, it was not President Trump, though some Democrats are trying to make it sound that way. Labour’s surge came weeks before May struggled to deal with Trump’s terrible tweets about terrorist attacks. Labour succeeded because turnout rose to its highest since 1997. The youth vote came out: One exit poll estimated turnout among voters under 35 at 56 percent, up 13 percent from 2015. Other estimates put youth turnout as high as 72 percent.

Why was turnout so high? Because Corbyn was able to generate excitement among Labour voters, especially the young. That’s in no small part because of this year’s Labour manifesto (the British equivalent of a party platform). Unlike other recent versions, mostly incrementalist documents that tweaked what came before, the 2017 edition is the boldest in decades: more money for the National Health Services and other major initiatives, a “jobs first” Brexit and free university tuition, financed by taxing corporations and the wealthiest. The manifesto and the campaign were summed up by their elegantly simple slogan: “For the many, not the few.” To be clear, May ran a terrible campaign, including an insultingly vague manifesto, but Corbyn and Labour were able to capitalize so well because they offered a real alternative.

If liberals are to succeed in the United States and elsewhere, they need high turnout, and especially high youth turnout. To do so, they need enthusiasm. Corbyn, Sen. Bernie Sanders (I-Vt.) and others who have succeeded at this don’t possess some mysterious charisma unavailable to everyone else. Unlikely voters will not be convinced to turn out for “the country is already great!” or other vague platitudes. They will come out for real solutions to their problems, whether those solutions are centrist, liberal, conservative or (perish the thought!) socialist.

“But American voters aren’t like British voters,” comes the reply. That’s partly true — but only partly. The ever-more-connected world means what was local is national and what was national is global. And there are few issues felt globally like inequality. In both countries, as elsewhere, people feel disenfranchised and unheard as many communities fall behind or remain left behind. Between 2009 and 2013 — the most recent years available — 85 percent of economic growth in the U.S. went to the top 1 percent. Young people in particular have come of age first watching an economic collapse driven by reckless speculation on Wall Street and deregulation in Washington and then seeing the financial firms’ wrongdoing go unpunished. Most voters believe something is very wrong with our current system. Offering more of the same is a path to political obsolescence. Offering new ideas is a path to success.

“Politics has changed,” declared Corbyn Thursday night, “and politics isn’t going back in the box where it was before.” He is right about British politics. If progressives apply the lessons of his success judiciously, U.S. politics will also change — for the better, for the many and not the few.