HOUSTON — Democrats looking to turn Texas blue in 2020 like to point to an election last year as a sign of hope.

No, not the Senate run by Beto O’Rourke, one of two Texans set to take the Democratic presidential debate stage in Houston on Thursday night. But rather that of Lina Hidalgo, a 29-year-old Colombian immigrant who defeated an incumbent Republican for county judge in Harris County, the county's top job.

Her unexpected victory in a populous county that counts Houston as its seat is the disruption national and local party officials hope to repeat across the state next year.

“Hidalgo defied all political naysayers,” Emmanuel Garcia, the executive director of Texas’ Democratic Party, said.

As Garcia and many other Texas Democrats see it, the political situation in the home state to two presidential candidates — former Housing Secretary Julián Castro, also the former mayor of San Antonio, and O’Rourke, a former congressman from El Paso — is far different than it has been in a while, driven in a big way by Latino voters.

The Democratic National Committee, which selected Houston as the site of its third primary debate on Thursday, has made clear its intention to court this potentially decisive group of voters.

According to a poll released Tuesday by Univision, 69 percent of Texas Latino registered voters said they would vote for the Democratic candidate or were leaning toward the Democrat, while 18 percent they'd vote for Trump.

Nationally, the poll found Latino voters favored former Vice President Joe Biden and Sen. Bernie Sanders of Vermont, at 22 percent and 20 percent, followed by Castro at 12 percent and Sen. Kamala Harris of California at 11 percent.

Bucking the national trend, the largest share of Texas Latino registered voters — 26 percent — said they'd vote for O'Rourke, followed by Biden (19 percent), Sanders (16 percent) and Castro (13 percent). Eleven percent, the next highest share, did not know.

Strong growth, ample room to go

The Hispanic vote grew 76 percent in Texas in 2018, and not only because of a population increase but also because a greater share of the larger Latino population went to the polls.

"Latinos can be the difference maker in Texas and many states across the country," said Tom Perez, Democratic National Committee chairman.

"That's one of the reasons we are having the debate in Houston. We want to send a clear signal that we look at Texas as a key battleground," Perez said. The debate is being held three days before Hispanic Heritage Month begins, in a state that is 39 percent Hispanic.

Republicans are paying attention as reflected in the formation of the super PAC Engage Texas. Its organizers have raised $9.6 million to register voters in the state and hired several staff members. A federal filing showed it had spent about $335,000 through June 30.

The super PAC's chairman is E.F. Mano DeAyala, a Houston attorney with clients in oil and gas, real estate, commercial business and other businesses, and its money comes from wealthy donors. He did not return a request for comment from NBC News.

One of the "wild cards?"

The state is shaping up to be one of the more interesting “wild cards” heading into the 2020 election, said Democratic pollster Matt Barreto, a principal at the Latino Decisions polling firm.

In last year’s midterms, Democrats flipped nine House seats and O’Rourke lost his Senate race to the Republican incumbent, Ted Cruz, by less than 2 percentage points. The state's other senator, John Cornyn, also Republican, has seen his approval ratings dip, and two-thirds of Texas Latinos disapprove of Pres. Trump, according to the Univision poll.

In nine Texas congressional districts viewed as potentially competitive in 2020, there are about 750,000 Latino votes, some registered, some not, that can be picked up, far outweighing the margin of victory in Republican and Democratic wins in 2018, Barreto said.

The landscape has also been altered by the domestic terror attack in El Paso on Aug. 3, when a gunman who later told police he was targeting Mexicans killed 22 and injured 26 at a Walmart.

According to police, the suspect posted a screed decrying a Hispanic invasion and a takeover of the state government by Hispanics and Democrats.

In the Univision poll, about 71 percent of Texas registered Latino voters surveyed agreed with the statement that "the El Paso shooter was a racist who was influenced by anti-immigrant and anti-Mexican statements made by President Trump." The poll has a margin of error of plus or minus 3.9 percentage points.

Democrats say that with those factors and the large pool of Latinos eligible to vote but not registered — some 4 million going into 2020 — there is room to push aside Trump and other Republicans who have held a tight grip on Texas’ elected offices for decades.

“The Latino vote is coming of age,” Garcia said.

The growing youth vote

Each year, 225,000 Latinos out of 340,000 Texans of all races turn 18. The majority of young Latinos are citizens and can vote.

About three quarters of those young Latinos 18 and older live in 13 metropolitan counties around Houston, Dallas-Fort Worth, San Antonio, Austin, El Paso and the Rio Grande Valley.

Annabelle Vasquez, 18, of San Antonio is part of that maturing Latino vote. On Monday, she joined a caravan to Houston with Castro supporters for her first political rally.

A political science student at Our Lady of the Lake University, Vasquez was turned onto his campaign by a news story she saw on Twitter recounting his presidential bid announcement.

“I thought it was really cool because he’s one of us. Since I’m Latina, I thought it was really cool to have someone represent us on the stage, the big stage,” Vasquez told NBC News by phone as she rode a bus to the rally.

Oscar Silva, Battleground Texas executive director, said the Latino vote is a “root” cause of the change being seen in Texas, where Latinos are on their way to being a plurality of the population in 2022 to 2024.

Battleground Texas is hoping to register about 250,000 Texas voters — the margin of O’Rourke's loss to Cruz — including 146,000 young voters and 131,000 voters of color.

Silva said the group is seeing Latinos go from unregistered to active voters in a shorter period — a single election season. Along the way, the group has learned to clear “barriers” to voting and seeing the Latino vote surge.

Hispanic early voting increased more than in any other ethnic group in 2020 as well, “an indicator of the priority that being civically engaged and an active voter is taking in the lives of our Latinx communities,” Silva said.

GOP: Trump will "prevail"

The Latino vote potential in Texas fits the Democrats' narrative that it is not a red state, but a state that doesn’t vote.

That's not how Republicans see things.

The party’s candidates can still can pull 35 percent or more of the Hispanic vote in state elections. A majority of Latino voters backed the relatively unknown and far less funded Lupe Valdez in her bid for governor last year, but she garnered 53 percent and Republican incumbent Greg Abbott got 42 percent of the state's Latino vote, helping him win the race.

Adryana Aldeen, a Republican analyst and consultant, said Hispanics will rise to support Trump because “like any other voter, they like to keep all their money in their pocket.” There may be disagreement with some of the things he’s done on trade and immigration, but the job growth and lower unemployment among Latinos will prevail, Aldeen said.

Sitting at a recent car club show in downtown San Antonio, Johnny Rodriguez, 55, who's in the Air Force Reserves, he doesn't like a lot of what Trump says, but he's still supporting him. "He's a businessman, so he knows what he's doing," Rodriguez said. Trump's rhetoric is not aimed at Hispanics, Rodriguez said, but at the "illegal alien."

Daniel Garza, president of the The LIBRE Initiative, a group whose limited-government positions align more with Republicans, said the recent El Paso shootings won't be factor when Election Day 2020 rolls around.

"When you go into the booth, you are still going to make a rational decision," Garza said. "The primary question is, will my life overall improve? The emotions of that week have long since disappeared by then."

The DNC's Perez has a long list of comebacks for Republicans' overtures to Latinos, from unaffordable health care hurting their economic recovery to attempts in the state to purge naturalized citizens from voter rolls to Trump calling Mexicans rapists. And then there is respect.

"He wants people in our community to be scared. He doesn't want them to vote," Perez said of Trump. "The Texas people stood up in 2018 and said I will not be cowed by you. You cannot deter me from my right to vote, and that is exactly what is going to lead us to victory."

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