Washington (CNN) Latino voters are angry at President Donald Trump. But that doesn't mean their anger will carry Democrats into House and Senate majorities in November.

Democrats had hoped that Trump's actions -- from attacking Mexicans at the outset of his presidential campaign to separating children from their parents at the southern border -- would galvanize Latinos who have historically skipped midterm elections.

Now, with just three weeks before the election, and early voting started in most key states, some Democrats are seeing warning signs that the anti-Trump sentiment isn't translating into votes with Latinos the way it has with women and African-Americans -- and that some candidates in key races have ignored the expensive and time-consuming task of turning out new Latino voters.

"People hate Donald Trump, but by itself, that isn't going to do it. You have to have the right messenger and the right message," said Cristóbal Alex, the Latino Victory Fund president and Hillary Clinton campaign veteran.

Privately, Democratic strategists say they fear their candidates in several key races are failing to reach Latinos. Among those they are worried about: Rep. Kyrsten Sinema, the Arizona Senate candidate who has cast what progressives see as troubling votes on immigration issues, might have to rely on Democratic gubernatorial hopeful David Garcia to reach Latinos. And Florida Sen. Bill Nelson, whose re-election campaign got off to a sluggish start as Republican Gov. Rick Scott beat him to the airwaves -- though he has recently made an increased effort to court Puerto Ricans in Florida.

Several congressional races concern Democrats, too, with heavily Latino districts in California, Texas, Florida, Arizona and Nevada potentially determining which party controls the House next year. At the top of the list is Florida's Miami-based 27th District, where former Bill Clinton health and human services secretary Donna Shalala -- who does not speak Spanish -- is trailing badly among Latino voters against Republican broadcast journalist Maria Elvira Salazar in a majority-Hispanic district that Hillary Clinton won by 16 percentage points in 2016.

In Texas, Rep. Beto O'Rourke, the online fundraising record-smasher challenging Republican Sen. Ted Cruz, is a fluent Spanish-speaker who has campaigned in regions Democrats have ignored for decades. He's "an honorary Latino," said Alex, a fellow El Paso native.

But a troubling sign for Democrats came in September, when Republicans won a state Senate special election in a heavily Latino district Clinton won by 12 points in 2016.

"All this talk about a 'blue wave'? Well, the tide is out," Republican Lt. Gov. Dan Patrick said at the GOP candidate's victory party that night.

Polls have also shown O'Rourke's name identification lower among Latino voters, and have him performing worse with Latinos than Clinton did two years earlier. Cruz, who is of Cuban heritage, has approached or hit 40% with Latinos in some polls -- denying O'Rourke the sort of overwhelming margin he'd need to win the state.

"Texas is a no-vote state. If Latinos turned out, they could determine the direction of that state," said Jessica Reeves, the chief operating officer of VotoLatino, a left-leaning nonpartisan group that registered more than 100,000 voters this cycle.

Demography isn't destiny?

For years, Democrats have hoped that the growing non-white population would remake the American political landscape in their favor -- turning red bastions in the Sun Belt like Arizona, Georgia and Texas into swing states and guaranteeing Democratic victories in Florida and Nevada.

That hasn't happened -- in part because white voters have abandoned Democrats almost as fast as Latinos have registered to vote. That explains why Trump later this week will visit rural Elko, Nevada, instead of a diverse population center like Las Vegas.

Another problem: Latinos still vote at much lower rates than other Americans. In 2016, Latinos made up 28% of the voting-eligible population in Texas but just 20% of the electorate -- people who actually turned out to vote -- according to the Census's Current Population Survey. In Arizona, Latinos are 25% of the voting-eligible population but were just 20% of the electorate. There were drop-offs in California, Florida and Nevada, too -- all states with marquee midterm races.

The makeup of each state's Latino electorate can vary widely. Florida is rich with conservative Cubans and Democratic-leaning Puerto Ricans. The Latino populations of states like Texas and Arizona feature United States-born children of more recent Mexican immigrants.

Progressive groups have mounted massive campaigns to register more Latino voters over the last two years. Democrats believe that some efforts -- like the Texas Organizing Project in Harris County, the home of Houston -- have actually changed the demographics of the electorate in time for the midterms.

"There's no data at all to suggest that Republicans are improving their image or that they're gaining any ground with Latino voters. The big question is just going to be, how high is the Latino turnout?" said Matt Barreto, the co-founder of Latino Decisions.

Candidates "need to throw away their likely voter model that their consultant gave them, and they need to start contacting people who normally do not get contacted -- the people who normally get ignored."

Some Republicans concede they face an enthusiasm problem headed into the midterms, too.

Jazmina Saavedra, a spokeswoman for Latinos for Trump in California, said the GOP is not "doing their job" in the state in energizing voters.

"We need to make sure that all the Republican registered voters go out and vote, and I bet you we can make a difference," she said.

How Democrats can turn out Latinos

At the root of Democrats' challenge with Latino voters, strategists said, is connecting national events with the outcomes of local elections.

"If we're able to connect with them, that goes a long way," said Ammar Campa-Najjar, the Democrat challenging California Rep. Duncan Hunter in San Diego's suburbs. "Minimal engagement could go a long way with the community -- it's right at the cusp."

Campa-Najjar is of Mexican and Palestinian heritage, and being a Latino candidate has helped, he said. As has hiring a "Dreamer" as his campaign manager, which he said has given his campaign a persuasive voice to allay the concerns of young potential voters who fear that by registering, they'll put undocumented family members in jeopardy.

He said he has focused on reaching younger Latinos in a state that sees itself as the heart of the anti-Trump resistance.

"They'll whip the family," Campa-Najjar said. "Older generation might be disenchanted. But if you can get the kid, you're going to get the household as well."

VotoLatino's Reeves said one challenge in turning out Latinos is "how much information they have and where it's coming from. There's also a lot of misinformation coming out about the Trump administration and what they're doing about family separations."

Alex pointed to Democratic Rep. Darren Soto fending off former Rep. Alan Grayson in an Orlando-area House primary this year on a surge of Latino votes as an example of how campaigns can court those voters. Soto was endorsed by the mayor of San Juan -- an influential voice for Puerto Rican voters -- and ran what Alex called a "culturally relevant" campaign with caravans and party buses.

"In primaries where Latino turnout did not meet expectations, it's generally where the candidate hasn't spent enough time dealing with the community and talking about issues that matter to the community," Alex said. "Or the investments just weren't there."