(CNN) Democrats have hit an unexpected speed bump in their drive to regain control of Congress: unsettling signs that the party may not generate as much turnout or support among Latino voters this fall as it expected.

Despite a procession of provocations from President Donald Trump -- from ending deportation protections for so-called "Dreamers," young immigrants brought to the country illegally by their parents, to his now-terminated policy that resulted in children being separated from their undocumented parents at the border -- a growing number of Democratic strategists are privately concerned that their candidates are not consolidating Latino support as much as they anticipated in several key races.

While cautioning that there is still time to reverse the trend, they point to signs of wavering Hispanic support and engagement in House districts in Texas, Nevada, Florida and California, and in Senate races in Texas, Nevada, Florida and Arizona.

"I still think it's a little too soon to push the panic button, but having said that, we are not seeing the types of numbers with Hispanic voters that we should be seeing with the most hostile person to ever hold public office against Hispanics as the President," said Fernand Amandi, principal at Bendixen & Amandi International, a Democratic polling firm that specializes in studying Latino voters. "And that in and of itself is a concern. I'm flabbergasted."

Private Democratic polling has found surprisingly lackluster results among Hispanics in such House races as the San Antonio-area House seat, where Democrat Gina Ortiz Jones is facing Republican Rep. Will Hurd; the exurban Los Angeles seat that Republican Rep. Steve Knight is defending against Democrat Katie Hill; and the battle in Orange County, California, for the open seat being vacated by Republican Rep. Darrell Issa.

Not all Democratic strategists see cause for alarm. Latino Decisions, another Democratic polling firm that specializes in Latino voters, and Stanley B. Greenberg, a veteran Democratic pollster, have each recently released separate surveys for Democratic organizations that find the party maintaining a healthy lead over Republicans when Hispanics are asked which party they intend to support in House elections.

Yet virtually everyone on both sides of this Democratic debate agrees on one point: Despite all his confrontational rhetoric and policies, Trump alone appears unlikely to reverse the usual falloff in Hispanic turnout during midterm elections, and he may not even widen the typical Democratic advantage among them in their vote preferences.

Neither public polls nor private research suggests an organic surge to the polls among Hispanic voters outraged by Trump is developing the way it appears to be coalescing among college-educated white women and African-American women. And that means Democrats face their typical challenge of energizing a community whose voter participation has remained stubbornly low.

"I think that the turnout is not guaranteed and all of the candidates and the interest groups have a lot of work to do," said Matt Barreto, co-founder and managing partner of Latino Decisions. "They don't want the anger to sit there and fester and turn into so much frustration that people don't feel that there is anything they can do."

From Florida to California

The alarms among Democrats over Hispanic intentions have been triggered partly by a series of recent public polls showing their candidates underperforming with those voters in several key races.

The findings start in Florida, where a recent Mason-Dixon survey showed Hispanics providing Democratic Sen. Bill Nelson only a narrow 44 percent to 39 percent lead over Republican Rick Scott. Republicans typically run better among Hispanics in Florida than elsewhere, because the state's large Cuban population has historically tilted right.

But Democrats have been improving because of their strength among Florida's growing Puerto Rican community, which has swelled again in the aftermath of Hurricane Maria. Exit polls found that Hillary Clinton beat Trump among the state's Hispanic voters by 27 percentage points in 2016. Yet Scott's aggressive outreach to the community has raised fears among Democrats that Nelson won't nearly match that margin with Latinos.

Several Texas polls have also shown surprisingly modest advantages for Democrat Beto O'Rourke over Republican Sen. Ted Cruz. The most recent Quinnipiac Poll gave O'Rourke just a 12-percentage-point lead over Cruz among Latinos. The nonpartisan Texas Lyceum Poll gave O'Rourke a comparable 15-point lead among all registered Latinos and a wider, but still subpar, 19-point lead among the Latinos the survey deemed likely to vote.

Joshua Blank, manager of polling and research at the University of Texas at Austin's Texas Politics Project, says that while most Texas Latinos support Democrats, there's no evidence yet that Trump's agenda is prompting much defection among the significant minority of them who consistently back Republicans.

"The reality is there are about one-third of Texas Hispanics who hold relatively restrictionist attitudes on immigration, support Republican positions, support Republican candidates ... and they were doing that while (Republican) politicians in this state were spending $800 million on border security and trying to pass sanctuary city laws with 'show me your papers' provisions," Blank said. "It's not that Trump comes along and Texas Hispanics are saying: 'What's going on here?' It's what has been going on here, and they have already arrived at those opinions."

In a third key Senate race, a public poll in Arizona , from OH Predictive Insights and the local ABC channel, found Democratic Senate candidate Kyrsten Sinema underperforming among Latinos against her most likely Republican opponent, Rep. Martha McSally. The survey actually found McSally leading with those voters, though few in either party consider that a possibility on Election Day, and OH Predictive Insights, which conducted the poll, cautions that the margin of error among Latino voters is high because the sample is small. Even so, some Democrats privately worry that Sinema has focused too much on convincing center-right white voters that she is concerned about border security and not enough on persuading Latinos she will defend their interests.

Also raising some eyebrows: The most recent NBC/Wall Street Journal national poll put Trump's approval among Latinos at 39 percent, well above his 28 percent share of the vote among them in 2016, according to exit polls.

Some Latino activists have long viewed public polls of their community -- including exit polls -- as unreliable and contended they tend to underrepresent respondents who speak mostly Spanish, a group that leans more toward Democrats. And other surveys show less reason for Democratic concern.

The most recent national Quinnipiac University poll, for instance, put Trump's Latino approval at 27 percent -- almost exactly equal to his vote among them -- and in Monday's weekly Gallup average, just 23 percent of Latinos approved. A recent Latino Decisions poll in 61 competitive House districts, conducted for a consortium of civil rights advocacy groups, found Democrats holding a roughly 40-percentage-point advantage among Latino voters.

Trump is 'in the strongman tradition'

Amandi says that despite these mixed signals in polling, he sees evidence that Trump and the GOP have maintained a beachhead of support among Latinos.

"My instant analysis is it's because of the economy," he says. "These are people who are not necessarily paying attention to every inning of political baseball. They are working. They are maybe getting a little bit more money."

Moreover, Amandi says, even Trump's belligerent style has found an audience among some Latinos, especially older men: "He's in the strongman tradition of the Latin American caudillo."

Yet Barreto's poll for the coalition of civil rights groups still found that about three-fourths of Latinos opposed both the border wall and Trump's now-abandoned "zero tolerance" policy and nearly 90 percent supported legal status for the "Dreamers." Barreto says the only reason Republican performance among Latinos might look relatively stronger in current surveys -- or on Election Day itself -- is if turnout among them remains low. The reason is that Latinos who lean Republican also tend to be older -- and thus more reliable voters in low-turnout elections.

"I have not seen any data that I would consider an accurate reflection of Latinos that Republicans are increasing (their share), or they will be over 25 percent of those voters," Barreto says. "The only reason it would be different is not that they are winning over more people; it would be if some Latinos who are Democratically leaning stay home."

Recent history offers evidence for that argument. In the House races during the low-turnout midterm elections of 2010 and 2014, Republicans won a higher share of Latino voters -- 38 percent and 36 percent, respectively -- than they did in House contests during the higher-turnout presidential years of 2016, 2012 and 2008 (from 30 to 32 percent), according to exit polls.

What about turnout?

That contrast highlights what remains the biggest concern about Latinos among Democratic strategists: Will they vote in sufficient numbers? In the 2010 and 2014 midterm elections, Latino turnout plummeted from its levels in the presidential elections just two years earlier: While about half of eligible Latinos voted in each of those presidential elections, a low number to begin with, the figure fell to under one-third in 2010 and a little over one-fourth in 2014.

Turnout among Latinos remained essentially stagnant at just under 50 percent in 2016 despite all of Trump's harsh rhetoric at the community. Barreto says his survey found a high level of anger at Trump among Latinos, especially younger generations, and he argues that anger has been a good predictor of heightened turnout. On the other hand, public surveys measuring how closely voters are following the election and whether they are certain to vote have mostly found Latinos still lagging other groups.

Poring over such ambiguous evidence, Henry Fernandez, a principal at the African American Research Collaborative, which studies issues relating to black voters, says the direction of Latino turnout this fall is not yet clear.

He says the increased Republican reliance on racially confrontational messages in the Trump era -- such as comments about the Central American gang MS-13 during the Virginia governor's race last fall -- has clearly prompted a backlash among African-American voters, who "respond most strongly" to any political argument that targets racial divisions, even if they are not the direct subject of the attacks.

Even though the MS-13 attacks failed to lift Republican Ed Gillespie during the Virginia race, the barrage of ads in Tuesday's Ohio special House election accusing Democrat Danny O'Connor of supporting "amnesty for illegals" and "open borders" makes clear that Republicans are committed to stressing racially infused immigration themes through the fall.

Whether that provokes a surge in Latino participation, Fernandez said, may turn on how the nonpartisan groups and Democratic organizations working on turnout respond.

"If the focus of the parties and those organizations is on the predictable electorate, that would be a mistake," he said during a recent conference call with reporters to release the Latino Decisions survey. "There are many more people who are at play who could be potential voters. It's not just a question of what will those folks do on their own, but where will investments be made to encourage people to get out to vote?"