A mariachi band, a Latino neighbourhood, Spanish language posters and bold immigration pledges: Bernie Sanders was pulling out the stops for Nevada’s Hispanic vote.

Short of dancing salsa, the Democratic candidate did all he could to woo this crucial constituency at a rally on a soccer field in Las Vegas on Sunday night.

He surrounded himself with Latinos on stage and promised to fight for agricultural workers and to shelter families from deportation. It signalled the start of an effort to narrow Hillary Clinton’s wide lead with the state’s Latinos.

There was just one problem: the audience at the Cheyenne sports complex was mostly white.

Latinos largely shunned the call to “feel the Bern”, leaving the crowd to dance stiffly to the Mexican music and a question mark over the campaign’s prospects in Nevada.

“I do notice it’s very white,” said Nathan Rudig, 33, a research analyst, eyeing fellow Sanders supporters. “He’s going to need the Latino and African American vote.”

Nathan Rudig attends the rally in Las Vegas. Photograph: Rory Carroll/the Guardian

Leslie Vega, 26, an insurance agent, lamented that she seemed one of the few Latinas to brave a cold desert night to hear the Vermont senator.

“I’m the only member of my family here,” she said. Vega believed Sanders could win the nomination but called the crowd “minuscule”. It numbered about 2,000 – more than what other White House hopefuls routinely muster but low by Sanders’ standards.

He injected numerous immigration references into his standard stump speech, which railed at the “rigged” economy and corruption.

“The truth is that these guys on Wall Street have more wealth and power than you can possibly imagine but there is something that we have that they don’t have and that is what is here tonight – the people.”

In his Brooklyn rasp, Sanders recalled his Polish parents’ struggles as immigrants and called undocumented workers “part of the fabric of America”. On Monday he was due to address a gathering of immigration activists in downtown Las Vegas.

The low-key Latino presence on Sunday underlined the challenge the Democratic socialist faces in mobilising significant Hispanic support.

His call for a “people’s revolution” has electrified progressive supporters across the US and put him ahead in New Hampshire, one of the states which will kick off the election for the Democratic presidential nomination.

Bernie Sanders in Las Vegas on Sunday. Photograph: MediaPunch/Rex Shutterstock

But in other states the 74-year-old lags badly with Latinos and African Americans, who prefer Clinton by a wide margin. Analysts say he is sunk unless he can close the gap.

A poll by impreMedia/Latino Decisions to be released on Monday will make sober reading for the Sanders camp. Some 41% of Latino registered voters in 14 battleground states either had not heard of him or had no opinion.

“That’s a big hurdle,” said Sylvia Manzano, of Latino Decisions. “He has a really tough task in terms of reaching voters.” Some 39% viewed Sanders favourably versus 20% who did not. Clinton’s respective numbers were 61% and 27%.

Even if Sanders gains visibility and favourable ratings, though, that may not translate into votes because Latinos seem loyal to the former first lady, who has forged deep ties to the community, said Manzano.

“She has been consistent. Her standing with this population remains really strong.”

Sanders’ presence in Las Vegas on Sunday and Monday showed his determination to break out of his box of white support – and the difficulties which await in the battle for next February’s Nevada caucus.

After months of low visibility in the state, during which Clinton established a formidable ground operation, the senator recently opened a campaign headquarters, with more than 10 offices to follow, said Emilia Pablo, the communications director.

“The campaign here is up and running. We’re ramping up. New volunteers are joining every single day. We’re the only ones putting out ads on Spanish-language radio. The more people learn about Bernie Sanders they more they tell friends and family.”

A largely Hispanic venue in northern Las Vegas would kick start the process at Sunday’s rally, said Pablo. “We want to give the Latino community a chance to see and hear Bernie Sanders.”

Liz and Darren said the lack of diversity at the rally was ‘a little concerning’. Photograph: Rory Caroll/the Guardian

Posters with slogans such as “unidos con Bernie” and “somos el 99%” greeted supporters but chatter was almost exclusively English. Darren, 35, a software developer who declined to give his surname, noticed the lack of diversity. “It’s a little concerning.” His companion Liz, 33, said low-income voters would back Sanders if they knew about his ideals. “It’s [about] getting the penetration.”

At a strip mall a mile from the rally, the Guardian interviewed 14 Latinos at random. Thirteen had never heard of Sanders.

“No idea,” said Jesus Arnao, 21, a landscaper watching the Eagles thrash the Cowboys in the Blue Mule bar.

“Who?” said Maria Jimenez, 51, folding clothes in a launderette. Her husband, Guadaloupe Terrazas, 51, knew one thing about Sanders. “He’s from Vermont.” Jimenez looked blank. “It’s a city,” said Terrazas.

It scarcely mattered: both supported Clinton. “I’m voting for her. She’s not racist,” said Jimenez.

Veronica Nunez, 30, leading two sons into Roberto’s Taco Shop for supper, echoed the sentiment. “Hillary is good. A friend of immigrants.” Memories of bountiful jobs during Bill Clinton’s presidency bolstered her enthusiasm.

I interviewed 14 Latinos at random 1 mile from Bernie rally. 13 never heard of him, incl Maria + Guadaloupe. pic.twitter.com/cIj4gNdVn4 — Rory Carroll (@rorycarroll72) November 9, 2015

Each candidate has wooed the Culinary Workers Union Local 226, the state’s most powerful union, with nearly 56% Latino membership. It has yet to endorse either, keeping both camps on edge.

Jon Ralston, a veteran analyst, said Sanders was scrambling to catch up. “He’s a big underdog here. His campaign just arrived and tried to hype hiring 25 to 100 people this week. That’s a wide range.”

It emerged on Sunday that the campaign’s recently appointed state director, Jim Farrell, was leaving. A spokesperson cited family reasons but did not elaborate on the timing, just three months shy of February’s caucus.

The Democratic frontrunner has had staffers in place since 13 April, the day she announced her candidacy.

“Clinton has been here for months, has the best people running her campaign, with experience from the ’08 and ’12 caucuses. She has endorsements and infrastructure,” said Ralston. “Yes, interceding events could change the dynamic. But assuming not, she will win Nevada.”

A big “H for Hillary” sign marked the entrance to the Clinton headquarters, a clutch of offices with a lived-in feel: coffee, candy and chips jumbled with phone lists, voting precinct maps and posters with adjectives about the candidate: “trustworthy”, “motivated”, “reliable”.

The state campaign director, Emmy Ruiz, 32, ran Clinton’s Latino outreach here in 2008 and Obama’s campaign in 2012. Nevada’s caucus system requires sophisticated analytics and different strategies for northern and southern Nevada, rural areas and counties, she said. “We’re applying best practice to caucus strategy.”

As Sanders supporters gathered on the soccer field, the Clinton campaign was training field teams, including a lesson in phone technique to a group of bilingual high school students. Not all came purely for love for the big H.

“I was told to come,” said one girl. “I’m doing community service.”