MIAMI — In the spring of 1989, as the outgoing mayor of Burlington, Vt., Bernie Sanders and his wife, Jane, traveled to Cuba on an eight-day trip, with the hopes of meeting the Cuban dictator, Fidel Castro.
The 47-year-old Mr. Sanders didn’t get time with Mr. Castro, but he toured Havana, met with its mayor and marveled that visitors could take a cab anywhere in the country. “The revolution there is far deeper and more profound than I understood it to be,” he said back home, according to The Burlington Free Press, and commended Cuba for providing free health care, free education and free housing.
Many older Democrats with sharp memories of the Cold War have been baffled and even offended by Mr. Sanders’s praise for the country — which is in the spotlight after he repeated some of it on “60 Minutes” this week — and it is one of the reasons they believe a self-described democratic socialist like Mr. Sanders would be a risky presidential nominee.
“It was a colossal blunder,” said Bob Squires, 70, of Murrells Inlet, S.C. “Loses Florida. If you look at Twitter, the people who had relatives come from Cuba, they have quite a different view. Bernie’s got blinders on.”
But for many younger progressives, the negative reactions to Mr. Sanders’s comments — which were also aired and debated in his 2016 presidential campaign — seem like boomer panic and a pernicious form of red-baiting, and reveal the divides within the Democratic Party.
“Socialism is a supposedly scary term that we’ve talked about so much, but we really don’t understand,” said Nolan Lok, 18, a chemistry major at the University of California, Los Angeles, where he cast a ballot early on Wednesday, ahead of its primary next week.
“In a society where technology is so important, where it takes fewer people to produce more things, we’re going to have to have a more socialistic society, where the government needs to step in more,” he said. “The government is going to be required to do more, and it’s something we should welcome, not be afraid of.”
This generational divide among Democrats was vividly apparent in interviews across the country this week assessing Mr. Sanders’s views and history, which included trips to the Soviet Union and Nicaragua as Burlington’s mayor as well as complimentary remarks about the Sandinistas. He has repudiated American foreign policy backing anti-Communist governments and resistance forces, and he has been fervently against war. But his remarks about Mr. Castro stand out, like his expression of amazement in 1989 that the Cubans he met “had almost a religious affection for him.”
Older liberals show varying support for Mr. Sanders’s positions, and the generational split was less apparent in South Florida, where many Cubans, Venezuelans and Nicaraguans do not like his views. Yet progressive voters born after the end of the Cold War — many of them people of color — dismissed the concerns about socialism as anachronistic and irrelevant.
For years in Washington, those left-wing views defined and to some extent diminished Mr. Sanders, an independent congressman and then senator who was widely regarded as a quirky outsider to the Democratic establishment. But now as the front-runner for the party’s nomination, Mr. Sanders is being pressured to explain his anti-imperialist worldview in the face of scrutiny and criticism from his rivals.
Mr. Sanders, 78, was pilloried during Tuesday night’s debate in Charleston, S.C., for his remarks on “60 Minutes’’ on Sunday, when he complimented the literacy programs Mr. Castro had enacted. Pete Buttigieg, the former mayor of South Bend, Ind., said Mr. Sanders had a “nostalgia for the revolutionary politics of the 1960s” and lamented the prospect of “reliving the Cold War.”
Mr. Buttigieg and other Democrats say Mr. Sanders’s views are not only misguided but also reinforce his image as a socialist, which will make him and other Democratic candidates down the ballot easy targets for President Trump and Republicans. And if he were to win the nomination, his stances could jeopardize his chances in Florida, the largest presidential general election battleground, where there is little room for appreciation of the 1959 Communist Cuban revolution.
Mr. Sanders stood by those positions at the debate, where he criticized U.S. policy in Latin America and repeated his praise for Mr. Castro’s literacy program.
“Occasionally it might be a good idea to be honest about American foreign policy, and that includes the fact that America has overthrown governments all over the world in Chile, in Guatemala, in Iran,” Mr. Sanders said.
Many older Cuban-Americans cringed at Mr. Sanders’s remarks, saying he sounded like an apologist for Communist indoctrination. And his views provoke particularly strong resistance in Miami, where the Cuban diaspora remains a powerful political force.
“I was offended by his ignorance,” said Mario Cartaya, a 68-year-old architect in Fort Lauderdale who left Cuba when he was 9 and is on the board of the Florida Democratic Party. “It is hurtful not just to Cubans, but it’s hurtful to every other Latin American who has fled their country because of the tyranny in those countries.”
“And it’s not an old comment that he can take back now, ‘He’s learned from his past mistakes,’ or whatever,” Mr. Cartaya added. “He said it now; he doubled down on it.”
The backlash was evident not only among conservative Cubans but also among liberal ones who helped former President Barack Obama win Florida twice.
“It’s actually incredible that it’s 2020 and we have to talk about this again,” said Fabiola Santiago, a columnist for The Miami Herald who wrote an emotional column about her experience as a young girl in Cuba. “We have to rehash Fidel, and we have to rehash the Cuban system. I don’t understand exactly what his motivation is.”
Mr. Sanders’s campaign does not view his remarks on Cuba, or his history of praising socialist governments, as problematic for him because it matters more to older moderate voters, a demographic Mr. Sanders already finds hard to reach.
Aides believe he is competitive in Florida in the Democratic primary, and the campaign plans to run commercials in all of the major media markets by next week. It is already deploying staff members to every region of the state.
In South Carolina, which holds its primary on Saturday and where many Democrats are evaluating candidates based on their perceived ability to defeat Mr. Trump, older voters examined Mr. Sanders’s unyielding views through the lens of electability.
“The man had his honeymoon in the old Soviet Union,” said Harvey William, 70, of Charleston, referring to a trip Mr. Sanders and his wife made there shortly after they married in 1988. Mr. William, who intends to vote for former Vice President Joseph R. Biden Jr., spoke bitterly about his experiences with socialism growing up in Guyana.
Voters at Mr. Sanders’s events, however, hardly mention his foreign policy views, instead ticking off his domestic policy agenda that includes implementing Medicare for all and making public colleges and universities tuition-free.
“Millennials don’t remember the Cold War,” said Maurice Isserman, a history professor at Hamilton College who has studied democratic socialism. “They don’t react in the same way to the word ‘socialist’ and associate it with totalitarian communism.”
Instead, young voters have experienced a structural shift in the economy, including the 2008 financial crisis and the crushing burden of college debt, that has given them a more critical view of capitalism, he said. Professor Isserman, though, warned that Republicans would use the senator’s comments to attack him in a general election.
“Bernie is not a communist,’’ Professor Isserman said. “He’s not a totalitarian. He’s a Scandinavian-style democratic socialist. But he’s also a product of the ’60s, and he has a kind of in-your-face confrontational style. It’s not so much politics as style that is his liability.”
Blanca Estevez, a member of the National Political Committee of the Democratic Socialists of America from Arkansas, said her political leanings initially confused her mother, given that the family fled left-wing military rule in El Salvador. But Ms. Estevez said she had made some inroads.
“I’ve been able to tie in my mom’s everyday values to the work that we do — telling her that she’s always shared everything she has, she’s always helped her neighbor, she’s made sure people have what they need where they’re down on their luck,” Ms. Estevez said. “Four years ago she hated Bernie Sanders. Now we have his sign in our yard.”
Even in Florida, Mr. Sanders has some support among younger Cuban-Americans, though they do not necessarily agree with his views on the Castro dictatorship. Defending Mr. Castro’s literacy program “kind of misses the bigger picture, which is the means don’t justify the ends,” said Julián Santos, 30, a legislative aide who was raised by Cuban immigrant parents in Hialeah, the most heavily Cuban-American city.
Still, Mr. Santos backs Mr. Sanders, as he did in 2016, because of his emphasis on addressing economic inequality and racial injustice.
In states like California, where Mr. Sanders has devoted time and resources to reaching out to the Latino community, some older Democratic voters have come around to him.
Concepción Cruz, a 64-year-old Mexican immigrant who voted early in Los Angeles this week, said she had backed Hillary Clinton in the last election. But her three sons have supported Mr. Sanders since 2015, and despite her initial intention to back Mr. Biden this year, she changed her mind after watching several debates.
“I want someone who is strong and experienced and will get the current president out,” she said. “We’re not going to become a socialist country. That’s not something I am worried about.”
Patricia Mazzei reported from Miami, and Sydney Ember from Winston-Salem, N.C. Katie Glueck contributed reporting from Charleston, S.C., Isabella Grullón Paz from New York and Jennifer Medina from Los Angeles. Kitty Bennett contributed research.