“I’ll have to hear the speech,” she said diplomatically of her rival’s coming address. But what about the argument of the title, to insist on democratic socialism? I asked. “I’ll have to hear his speech,” she said again.

That Sanders would lean into democratic socialism—and that he’d do so now—is surprising only to people who don’t know him. He wants this fight. He believes that he’s more right than most insiders are ready to acknowledge, based on his own successes and based on how he’s defined so much of the larger Democratic agenda these past four years—not to mention all the polls that show support among young people for socialism.

Read: Democratic socialism is surging in Iowa ahead of 2020

Of the two dozen Democrats running for president, some are ready to sign on to ideas Sanders has pioneered, such as Medicare for All, but none agree with democratic socialism as a way to govern, or as a pitch that will defeat President Donald Trump. Former Colorado Governor John Hickenlooper, who was booed for condemning socialism two weeks ago in a speech before the California Democratic Party, laughed at the title of Sanders’s speech when I read it to him. Senator Michael Bennet of Colorado let out an exasperated chuckle. “I don’t think the American people even know what that means,” he told me. “Nobody in my town halls talks about democratic socialism versus oligarchy and authoritarianism.” When I read the title of the speech to Senator Kamala Harris of California on Monday after an event in Dubuque, she responded with a simple “Huh.”

At a CNN town hall in April, Sanders defended democratic socialism at length in response to a question from the daughter of a Soviet refugee. He distinguished his economic agenda from “authoritarian communism,” framing his beliefs instead in the tradition of Franklin D. Roosevelt. This past Sunday, on CNN again, Sanders elaborated: “I think it’s important for the American people to understand what my definition is of democratic socialism. And it's certainly not how Donald Trump defines it,” Sanders said, adding, “When I talk about democratic socialism, it means a vibrant democracy and an economy that works for all, not just the people on top.” That same sort of language, linking his ideas to a tradition in the Democratic Party, will be part of his speech today, according to Sanders’s senior adviser Jeff Weaver. “There are a lot of democratic socialists in the Democratic Party. There are now, and there always have been,” Weaver told me after looking over a final draft of the speech yesterday. Weaver said that Sanders is planning to take on the “socialism bogeyman” argument directly.

Read: Bernie Sanders makes his pitch for socialism

This new speech has long been in the works, Sanders’s aides tell me, and they say it doesn’t have anything to do with his recent drop in the polls as Warren rises. They say they’re not concerned that he’s not showing signs of breaking through past his solid core of support. He’s scheduled to deliver the speech in Washington, D.C., on the campus of George Washington University, rather than at home in Vermont or out in a swing state. Aides say the D.C. setting is an attempt to convey his seriousness on the subject. They want this to be a major signpost in his 2020 campaign, an opportunity for Sanders to lay out why he’s running with an argument no one else can or would make as forcefully, and to dare the rest of the field to oppose him. They believe this speech has the potential to re-center the dynamics of the race around him, and that the other candidates will regret any of their laughter and questioning of it to me over the past few days.