Democratic presidential candidate Joe Biden has a big problem in Florida — and it has Democratic insider Bernie Sanders quietly whispering that the Biden campaign is blowing the Democrats chances.

But during her first trip to Florida as Joe Biden’s running mate last week, Sen. Kamala Harris, D-Calif., did little to court this region’s booming — and politically influential — Latino population. She instead focused on African American leaders waiting at a historically Black university in Miami Gardens.

“You truly are the future of our country,” Harris said into a megaphone after the motorcade pulled up to Florida Memorial University, where a marching band serenaded her ahead of an hourlong discussion with local Black leaders. “You are the ones who are going to inspire us and fight for the ideals of our country.”

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In America’s leading presidential battleground, there’s mounting anxiety among Democrats that the Biden campaign’s standing among Latinos is slipping, potentially giving President Donald Trump an opening in his reelection bid. That’s fueling an urgent effort by Biden, Harris, and their allies to shore up older voters, suburbanites, and African Americans to make up for potential shortcomings elsewhere.

New York billionaire Mike Bloomberg committed over the weekend to spend at least $100 million in Florida to help the Democratic ticket. Biden is scheduled to make his first visit to the state as the Democratic nominee on Tuesday, where he will hold a roundtable with veterans in Tampa before attending a Hispanic Heritage Month event in Kissimmee.

If Biden reclaims the upper Midwest for Democrats, he won’t need Florida to capture the presidency. But Trump has virtually no path to reelection without it, which is why the state remains a top priority for Democrats.

Concerns about Biden’s strength in Florida were driven in part by an NBC-Marist poll released last week, which found Latinos in the state about evenly divided between Biden and Trump.

Former Secretary of State Hillary Clinton led Trump by a 59% to 36% margin among Latinos in the same poll in 2016.

Trump ultimately beat Clinton in Florida by just over 1 percentage point.

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Hispanic voters in Florida tend to be somewhat more Republican-leaning than Hispanic voters nationwide because of the state’s Cuban American population. Nationally, little public polling is available to measure the opinions of Latino voters this year and whether they differ from four years ago.

But allies closest to the Latino community said there are reasons to worry.

“Right now, I think the Biden campaign has work to do,” says Javier Fernandez, a Democrat running for the state Senate in Miami-Dade County, where 7 in 10 residents identify as Latino or Hispanic. “I don’t know that they’re super excited about Joe Biden.”

Sen. Bernie Sanders, who led among Latinos during the early stages of the Democratic primary, warned on Sunday that Biden should be “reaching out more aggressively to grassroots Latino voters.”

That would require a targeted — and expensive — effort that acknowledges the complexities of the Latino vote in Florida. A winning campaign likely requires varied outreach to Cuban Americans, Dominicans, and Venezuelans in Miami along with first- and second-generation Central American immigrants around the state and displaced Puerto Ricans who settled in central Florida after Hurricane Maria.

The campaign has responded in part with ads featuring narrators with different accents to appeal to various backgrounds.

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Some on Biden’s team privately acknowledge he may not win over Latinos by the same margins as Clinton, although they are not conceding defeat. Senior strategist Cristobal Alex said the campaign has been pounding airwaves with Spanish-language advertising for months in addition to launching “Latino leadership councils” across the country.

“As we get closer to November you’re going to see an even greater amount of activity to turn out Latino voters,” Alex said.

Ashley Allison, who leads Biden’s constituency engagement, said the campaign has already assembled more than 20 coalitions that include seniors, progressives, veterans, and Native Americans, among others. Biden’s team has aggressively courted Black men and Black women in recent days as well, featuring virtual events with Harris and celebrities like actor Don Cheadle.

“We don’t have to focus on just one pathway, just one set of specific voters. We have the ability to expand the map and the coalition,” said Becca Siegel, Biden’s chief analytics officer.

Still, Trump is sensing a potential vulnerability. During a campaign swing through the west, he held a roundtable discussion with Latinos in Las Vegas on Sunday and has another scheduled Monday in Phoenix.

“They understand the situation at the southern border. They want people to come in, and so do I, but they want them to do it legally,” Trump told a small group of supporters in Las Vegas. “While Joe Biden has failed, I have delivered for Latinos.”

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Ernesto Palacios, a 70-year-old U.S. citizen of Cuban decent, said he voted for Trump in 2016, but won’t do so again.

But Palacios said his opposition to Trump does not mean he will vote for Biden. He described Biden as “soft” and raised concerns about the push to defund the police.

One of Palacios’ neighbors, Juan Guzman, fled Fidel Castro’s rule in Cuba at 15. He called Biden “a socialist” and said voting for him was out of the question.

Carlos Odio, a co-founder of the Democratic polling firm Equis Labs, said Biden will comfortably win the Latino vote, but that his backing in the community has remained soft enough that he may lose support by people simply not going to the polls — a trend that could be decisive in states like Florida.

“This is in so many ways a mobilization question for Joe Biden,” Odio said. “Folks aren’t necessarily deciding between Donald Trump and Joe Biden but deciding between voting and not voting.”

Biden allies in the Latino community are worried.

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Domingo Garcia, the president of the League of United Latin American Citizens, said Latino voters have responded to Trump’s embrace of religious conservative positions, and his warnings of protest-related violence and socialism.

“You need a message that hyper-excites the Latino community such as health care for all or dealing with immigration in first 100 days. Biden has been really lukewarm on those issues,” Garcia said.

Some skepticism of Biden among Latinos stems from the policies of the Obama administration. Under pressure from pro-immigration protesters during the Democratic primary, Biden apologized for the high rate of deportations when President Barack Obama was in the White House.

But on several specific policies, Biden has refused to adopt the most liberal positions in his party.

He argues, for example, that crossing the U.S. border illegally should be prosecuted criminally rather than as a civil offense. He’s also not seeking free college or free health care for people in the county illegally — despite Trump’s suggestion that he is.

During her swing through Florida last week, Harris did not ignore the Latino community altogether.

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She made an unscheduled stop at a local Venezuelan restaurant for about 20 minutes to pick up lunch. She sprinkled a few Spanish words during brief conversations with the lunch crowd, introducing her husband as “mi esposo” and saying “gracias” to one man who welcomed her to “Doral-zuela.”

“There are so many important issues,” Harris told him without being specific. “There’s so much at stake.”

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The Associated Press contributed to this article