Bernie Sanders has surged in the Democratic primary campaign with a cry of “Feel the Bern”, but when it comes to Latinos the Vermont senator is feeling the wrong kind of heat.

Sanders has attracted huge crowds and streaked past Hillary Clinton in the crucial state of New Hampshire but dismal ratings among Latinos could help doom his insurgent candidacy.

Most have not heard of him, creating a big hole in his path to the presidential nomination. Clinton, in contrast, enjoys formidable name recognition and support.

“Polling by Latino Decisions has found that Bernie Sanders has very, very low name recognition and following among Latinos,” said Matt Barreto, a co-founder of the leading Latino political opinion research group. “As a senator from Vermont, he does not have a strong history of doing outreach to the Latino community, or being involved on Latino issues such as immigration or bilingual education.”

That verdict will be a wet blanket to supporters who have begun to believe the self-described democratic socialist can go all the way to the White House. It raises the spectre of Howard Dean, another Vermont insurgent who electrified progressive enclaves in the 2004 primary race before flaming out.

Sanders has recognised the danger and ramped up efforts to connect with Latinos, adapting rhetoric and tactics originally aimed at white liberals. The shift was on display earlier this week when Latinos joined a rapturous, diverse crowd at the Los Angeles memorial sports arena.

“I truly believe he represents the people. He’s not beholden to corporate interests. He’s the one representing minorities across the US,” exulted Yuliana Miranda, 23, a teacher, amid deafening chants of “Bernie”.

The question is whether the campaign can attract enough people like Miranda, a newly recruited activist who has joined a grassroots group in Los Angeles. The omens are mixed.

A survey of Hispanic voters conducted last month for Noticias Univisión found that 73% would vote for Clinton in the Democratic primary. Some 68% did not know or had not yet formed an opinion about Sanders. In a separate Fox News poll earlier this month Clinton led Sanders by 29 points among all Democratic voters – and by 50 points among non-white Democratic voters.

Barack Obama lost the Latino vote by 26 points to Clinton in 2008 but compensated with overwhelming endorsement from African Americans – a remote prospect for Sanders. He needs to make inroads with both groups.

The 73-year-old has momentum. He has drawn more than 100,000 people to recent rallies, an astonishing number this early in a campaign; won a major union endorsement; and a poll released by Franklin Pierce University and the Boston Herald showed him leading the former secretary of state 44% to 37% in New Hampshire.

When Latinos learn more about Sanders they will learn he favours immigration reform, a federal minimum wage, expanded social security and free healthcare and college tuition – things they tend to favour, said Mark Lopez, director of Hispanic research at the Pew Research Center. “Latinos are more likely to be supportive of a bigger government providing more services.”

The senator’s fulminations against poverty and Wall Street fat cats will also play well since there are more Latino children living in poverty than black or white children, said Lopez. “So he’ll be able to make some inroads given the concerns Latinos have. But how much, I don’t know.”

Sanders’ outreach to African Americans following Black Lives Matter protests has been well documented. Less noted has been his Latino lobbying.

He outshone Clinton last month at the National Council of La Raza’s annual conventionin Kansas City, talking about his Polish father’s immigrant struggles, his impoverished upbringing, his civil rights record and how the federal government could ease poverty and hardship.

He sat down with Jorge Ramos, the influential Fusion and Univision host, and said he if elected he would bring “11 million undocumented people out of the shadows”.

At the rally in LA, a metropolis about 44% Latino, Sanders moved up a gear. Maria Barrera, the 31-year-old leader of the Coalition for Humane Immigrant Rights of Los Angeles, warmed up the crowd with a tearful plea for comprehensive immigration reform. “Bernie Sanders is speaking up and we say thank you, but remind him that as president he should also remember the people in the shadows,” she said. Sleeves rolled up, his voice hoarse, Sanders vowed to not forget. “They cannot continue to be exploited. They cannot continue [to be denied] legal rights.”

The senator has an exposed flank on immigration, however, for suggesting that increasing the number of immigrants could depress wages and take away American jobs.

“That’s how Republicans talk. I’m very concerned about the way he’s coming to this debate,” said Cristina Jimenez, managing director of United We Dream, which calls itself the US’s largest immigrant youth-led organisation. “No Latino will embrace an analysis that says immigrants are at fault for lower wages.” She urged him to meet undocumented leaders and visit a deportation centre.

For Sanders to amass enough delegates to nab the nomination, the “Feel the Bern” spirit must inspire a critical mass of Latino activists to erode Clinton’s lead.

Those who are already converted concede it may be tough. “It sounds like a dream but it’s not impossible. That’s how Obama started,” said Carmen Valdivieso Hulbert, 65, a Peruvian-born retired journalist who has helped launch a Latinos for Bernie group in Brooklyn.

Once people learn about his record and policies, especially economic policies, through social media and old-fashioned canvassing they will embrace him, said Valdivieso. “Latinos just need to know him. It’s taking a little time but the traction is there. Give us a couple of months. It’s going to grow fast.”

Another New York activist, Cesar Vargas, a writer and producer, agreed. “A couple of months ago I’d have said he didn’t stand a chance. But when people know more about him they switch from Hillary. It’s a matter of exposure.”