In March 2016, Bernie Sanders stood on a debate stage in Miami with Hillary Clinton and faced questions about his decades-old comments about Fidel Castro of Cuba and Daniel Ortega of Nicaragua.

The moderator asked the Democratic presidential candidate whether he regretted the positive things he’d said about communist and socialist leaders in 1985. “The key issue here was whether the United States should go around overthrowing small Latin American countries. I think that that was a mistake,” Sanders replied, not directly answering the question.

Three years later, the senator from Vermont, who is making another run for the White House, is again facing scrutiny for his comments about communist leaders and countries, as well as what it means for him be a democratic socialist, a label no other prominent presidential candidate has embraced.

This time, Sanders is in a very different political landscape — one that could focus more on his rhetoric in a way that some Democrats fear could play into President Trump’s hands.

“Donald Trump cannot win reelection in 2020. Democrats can lose it,” said Edward G. Rendell, a former Pennsylvania governor and a centrist Democrat. “The only way [Trump] wins is by scaring the American people into thinking that our candidate and our party is so progressive, they are going to turn us into a socialist government.”

Some Democrats worry that Sanders’s presence in the Democratic primary will allow him to influence party’s message even though he’s an independent, and his reluctance to call Venezuelan President Nicolás Maduro a dictator has been criticized by Democrats as well as Republicans.

At the same time, the socialist label may not carry the same opprobrium in some quarters as in earlier years. A new generation of Democratic activists is advocating an unabashedly liberal agenda, and the Cold War is fading further into the rearview mirror.

Trump and his Republican allies, however, are betting that the idea of socialism will still turn off many voters, and they’ve embarked on a campaign to paint the Democratic presidential hopefuls as far-left extremists, with Sanders as the prime example.

Ben Rhodes, who was President Barack Obama’s deputy national security adviser, said Sanders has “a way to push back” on the GOP attacks, because his brand of socialism does not resemble that of Maduro and his ilk.

“I think the challenge for Bernie is just going to be differentiating his brand of social democratic policies from the corrupt turn — and authoritarian turn — socialism took in parts of Latin America,” Rhodes said.

Sanders’s refusal to call Maduro a dictator or urge his ouster could complicate that, however. Sanders is also facing criticism from members of both parties for his unwillingness to recognize opposition leader Juan Guaidó as the interim president of Venezuela, as Trump and Democratic leaders have done.

Another complicating factor is that Democrats have attacked Trump for being dangerously accommodating toward dictators such as North Korea’s Kim Jong Un, whom the president is meeting with this week at a summit in Vietnam, and any perception that Sanders is not tough on Maduro could muddle that message.

During a CNN town hall meeting Monday night, Sanders explained his position toward Maduro by citing various questionable U.S. interventions in Central America in the 1980s, saying it would be terrible for the United States to repeat those mistakes by invading Venezuela or imposing a leader on the country.

“It’s fair to say that the last election [in Venezuela] was undemocratic, but there are still democratic operations taking place in their country,” Sanders said. “What I am calling for right now is internationally supervised, free elections.”

Sanders is likely to face far more scrutiny in this campaign than in 2016, when he was a relatively obscure challenger of a powerful primary foe. This time, he is among the better-known figures in a large field of Democrats, all of whom would love to cut into his support.

And many Republicans see an opening not only to attack Sanders but to put the rest of the Democratic field on the spot. They are publicizing the senator’s comments on social media and circulating video of him speaking about Castro and Ortega in 1985.

“The rest of the 2020 candidates have adopted so much of his socialist agenda, it’s only fair to ask them whether they agree with his radical foreign policy views as well,” Michael Ahrens, a Republican National Committee spokesman, said in a statement.

One video making the rounds shows a 1985 interview of Sanders by CCTV in Vermont, in which he said some positive things about Castro’s leadership in Cuba as he reflected on the failed Bay of Pigs invasion.

“Everybody was totally convinced that Castro was the worst guy in the world, that all the Cuban people were going to rise up in rebellion against Fidel Castro,” said Sanders, who was then mayor of Burlington, Vt. “They forgot that he educated their kids, gave them health care, totally transformed the society.”

He continued, “You know, not to say that Fidel Castro and Cuba are perfect. They are certainly not. But just because Ronald Reagan dislikes these people does not mean to say that the people in their own nations feel the same way.”

In the same interview, Sanders called Ortega, the leader in Nicaragua, “an impressive guy.”

Asked whether he regretted those sentiments, Sanders’s campaign pointed to his original comments, offering no new clarity on the matter. An aide said the senator’s careful word choice on Venezuela is rooted in his strong opposition to U.S. military intervention in the region.

Some of his Democratic presidential rivals have sounded different notes, even as they have taken similar overall positions on the Venezuela crisis.

Sen. Elizabeth Warren (Mass.) has called Maduro a “dictator.” Sen. Kamala D. Harris (Calif.) has railed against “Maduro’s dictatorial regime,” urging Trump to extend temporary protections to Venezuelan immigrants.

Democrats cite this week’s summit between Trump and Kim to argue that it’s the president who has a soft spot for tyrants, including Russia’s Vladi­mir Putin and Saudi Arabia’s Crown Prince Mohammed bin Salman.

“I think that right now what this Trump administration is showing us is an irresponsibility when it comes to everything from North Korea to dealing with the Russians,” Sen. Cory Booker (N.J.) told reporters recently.

Some Republicans have also criticized Trump’s relationship with those countries, but that has not diminished their critique of Sanders. Earlier this year, Rep. Liz Cheney (Wyo.) became entangled in a back-and-forth with Sanders, tweeting at him, “Socialism is a fraud. It steals power from the people & gives it to the government.”

At Monday’s CNN town hall event, Sanders did not back away from the democratic socialist label, saying it stands for such principles as health care for all, accessible college and retirement security.

“What democratic socialism means to me is having, in a civilized society, the understanding that we can make sure that all of our people live in security and in dignity,” he said.

One of Sanders’s selling points, in the quickly expanding Democratic presidential field, is that he spoke out for such policies as Medicare-for-all and tuition-free college long before they were embraced by the other hopefuls.

Although that could set him apart from more recent converts, his long trail of commentary on socialism and communism could also distinguish him. Whether that will help or hurt in this turbulent political climate is less clear.

“There’s so much interest in the Democratic field,” said Scott Brennan, a Democratic National Committee member from Iowa. “Everything that anybody has ever said . . . it’s preserved forever.”