The prospect that Vice President Biden might choose as his running mate a veteran of Cuba’s Venceremos Brigade reminds us of how much we miss Lane Kirkland. He was the last great anti-communist leader of Big Labor. A Democratic Party power, he died in 1999, alas. He would have known what to advise Mr. Biden in respect of potential running mates like Congresswoman Karen Bass.

Ms. Bass is not the first Venceremos veteran to vie for high office. The “brigade” helped Cuba court idealistic Americans for such revolutionary tasks as harvesting sugar cane. In the 1990s, President-elect Clinton came close to tapping a brilliant educator, Johnnetta Cole, for a spot in his cabinet — until it emerged that she’d been on the Venceremos Brigade’s national committee.

The Johnnetta Cole story was broken by David Twersky of the Forward. He, like Kirkland, is gone now. He had been active in pro-labor, Zionist politics, and was the Forward’s Washington correspondent when he landed the Cole story (he was later foreign editor of the Sun). Anti-communist socialists had tipped off Twersky about Ms. Cole. Mr. Clinton’s decision to drop her caused a brief stir.

We are not suggesting Ms. Cole or Ms. Bass sought to deceive, respectively, Mr. Clinton or Mr. Biden. Neither did so, so far as we know. Ms. Bass reportedly warned Mr. Biden that the Venceremos story might come up. Nor are we suggesting that hard left figures need to be read out of American politics. Both our leading parties have been enriched over the years with veterans of the hard left who learned from their experiences.

We are suggesting, though, that with left-wing violence burning through our cities, this is no time to let down the guard. It’s not just Mr. Biden and Ms. Bass. We warned of the absence of Lane Kirkland’s kind of savvy in 2008, when candidate Barack Obama made his trip to Berlin. We worried then that Mr. Obama lacked such advisers from the anti-communist labor movement as those who guided President Kennedy in Berlin.

It’s not academic. If Mr. Biden wins the presidency, he is going to come under enormous pressure to, say, recognize Cuba’s communist regime. The Democrats in the House were all too eager to do so. Secretary of State Kerry was infected with the idea. He suggested our relations with Cuba had been suspended in Cold War politics as in “amber.” Where would a Biden-Bass administration take us on Cuba?

The communist island is a marker in a broader struggle. We understand that Ms. Bass is a significant figure in the House. And that she told NBC News: “I’m not a socialist. I’m not a communist. I’ve belonged to one party my entire life, and that’s the Democratic Party.” At the rate the Democratic Party is going, though, the distinction she seeks to draw is getting finer with every passing election.

A terrific dispatch about Ms. Bass’s involvement with Cuba is up at the Atlantic (now edited by an erstwhile colleague of Twersky at the Forward, Jeffrey Goldberg). The Atlantic’s reporter, Edward-Isaac Dovere, quotes a Democratic consultant referring to comments Senator Sanders recently made to the effect that in respect of Castro’s government “it’s unfair to simply say everything is bad.”

“Fairly or unfairly,” Mr. Dovere quotes the consultant, Fernand Amandi, as saying, “Karen Bass’s history on this subject makes Bernie Sanders look like Ronald Reagan.”

Ms. Bass tells the Atlantic that, with all that’s going on today, including the pandemic, she finds it hard to believe that her record on Cuba is “what’s going to be on people’s minds in the next hundred days.” Hmmmm. Mr. Dovere also quotes a Cuban American radio host who is, Mr. Dovere writes, popular with Cuban Americans in Florida as cautioning that “it’s not only about Cuba.”

“It’s about the socialist narrative,” the radio host, Roberto Rodriguez Tejera, tells Mr. Dovere by email. “She is the poster person for it. A dream come true for the Republicans. It’s also about any independent voter, anywhere in the country, who may be afraid of a total takeover of the Biden presidency by the radical left.” It’s hard to imagine that Lane Kirkland could have put it any more clearly.