Mette Frederiksen, the prime minister of Denmark, had returned from Ukraine hours earlier and was munching on a baby carrot when I walked into her office on a recent Wednesday afternoon. She laughed as she finished the carrot, evidently not expecting a visitor quite yet.

“I need vegetables,” she explained.

The trip was a whirlwind — a flight into Poland, then a train into Kyiv, all of it kept secret until Frederiksen was across the border. It was her fifth trip to Ukraine since the war began, and she made it to honor the 1,000th day of resistance to Russia’s invasion, a day that happened to coincide with Frederiksen’s 47th birthday. While there, she visited wounded soldiers in a hospital, and she appeared at a news conference alongside President Volodymyr Zelensky to announce Denmark’s latest aid package for Ukraine. Relative to the size of its economy, Denmark has donated more to the war effort than any other country.

Generous support for Ukraine is only one way in which Denmark has become an outlier. Since President Trump won re-election in November, Frederiksen has become a global symbol of opposition to him, thanks to her rebuffing his call for Denmark to turn over control of Greenland. But the main significance of Frederiksen and her party, the Social Democrats, has little to do with aid to Ukraine or a territorial argument in the North Atlantic. Over the past six years, they have been winning elections and notching policy victories that would be the envy of liberals worldwide, and doing so at a moment when the rest of the West is lurching to the right.

In Hungary, Prime Minister Viktor Orban has changed laws and marginalized critics to help him remain in office. In Austria, Britain, France, Italy, the Netherlands, Sweden and elsewhere, the far right has grown. In Germany’s election on Sunday, the governing center-left party finished third, behind the center right and far right. In both Canada and Australia, polls suggest that center-left governments will lose elections this year. And in the United States, Joe Biden left office with dismal approval ratings, and Trump won the popular vote for the first time last year. In each of these cases, a major explanation is that working-class voters have drifted from their historical home on the political left and embraced some mix of populism, nationalism and conservatism. Over the past several years, there is arguably not a single high-income country where a center-left party has managed to enact progressive policies and win re-election — with the exception of Denmark.

Since the Social Democrats took power in 2019, they have compiled a record that resembles the wish list of a liberal American think tank. They changed pension rules to enable blue-collar workers to retire earlier than professionals. On housing, the party fought speculation by the private-equity industry by enacting the so-called Blackstone law, a reference to the giant New York-based firm that had bought beloved Copenhagen apartment buildings; the law restricts landlords from raising rents for five years after buying a property. To fight climate change, Frederiksen’s government created the world’s first carbon tax on livestock and passed a law that requires 15 percent of farmland to become natural habitat. On reproductive rights, Denmark last year expanded access to abortion through the first 18 weeks of pregnancy, up from 12 weeks, and allowed girls starting at age 15 to get an abortion without parental consent.