Sri Preston Kulkarni has just moved into his campaign headquarters, which for now could hardly be more bland: a faceless office with blinds on the windows in a tucked-away suburban Houston business park.

Not far away, though, are a Muslim community centre, a Korean market, Hindu temples, Vietnamese, Chinese, Indian and Mexican restaurants – reminders that this sprawling Texas metropolis is one of the most diverse urban areas in the nation.

Houston’s fast-growing south-western suburbs are, for Kulkarni, who is seeking the Democratic nomination for a Texas’ congressional district, an American success story: a symbol of multicultural tolerance and prosperity, of a country that welcomes the world.

And it is these shifting demographics that have long offered hope for Democrats that they might soon overturn Republican hegemony in the state. The Republicans have dominated for the last 30 years but their grip on this emblematic state may be about shift.

The state’s Hispanic population is predicted to outnumber white residents as soon as 2022. Given the current administrations’ position on immigration and President Trump’s most recent racist attacks on politicians of color the rise in the number of Hispanics voters may well favour Democratic candidates.

The El Paso killings will hasten the process of non-white communities in Texas mobilizing to exert greater political influence, said Antonio Arellano, interim executive director of Jolt, a Texas-based not-for-profit group that aims to boost political engagement among Latino people.

“Latinos are coming out to vote like never before because our lives genuinely depend on it. We are being attacked not just all the way at the top in the highest office in the land, but that hatred and discriminatory rhetoric is spewing into our communities and now what we’re seeing is bloodshed in our streets,” Arellano said.

“The reason we are under attack is because we are powerful,” he added. “Right now, 50% of all Texans under the age of 18 are Latinos. And with that comes a lot of political power.”

It is not news that Texas’ rural parts are firmly Republican while the urban cores of five of its six biggest cities are Democratic. But Democrats are making inroads in cosmopolitan suburban areas where Trump is unpalatable to those who would normally lean Republican.

Trump won Texas by nine points in 2016, but he is relatively unpopular in the state. A University of Texas/Texas Tribune poll conducted in June found that 50% of respondents plan to vote for Trump in 2020 – and 50% do not.

“Donald Trump is the worst thing that’s happened to the Texas Republican Party in recent memory. Without his presence in the White House we wouldn’t be having much in the way of discussions these days about turning Texas purple,” said Mark Jones, a political scientist at Rice University.

Like former Texas congressman and current presidential hopeful Beto O’Rourke, Kulkarni’s political messaging centers on inclusivity, respect for differences and engaging young people. It contrasts starkly with the racial divisiveness promoted by Donald Trump and senior Texas Republicans long before the recent massacre at an El Paso Walmart, allegedly by a gunman who chose his targets because he believes the state is under “Hispanic invasion”.

“To me it’s hate speech. That’s what it is when you talk about entire races, entire religions that way, you’ve got to call it out for what it is,” Kulkarni said. “When it incites people to violence you have to expect those kinds of results. In terms of what we can do on our side to counteract that, you talk about what America really is.”

A former diplomat, Kulkarni, 40, is the son of an Indian novelist and academic who immigrated to America in 1969 and a white mother whose family came to the US in the 1600s. Through her he is descended from Sam Houston, who in 1836 became the first president of the Republic of Texas.

Kulkarni is trying again in 2020 after he lost the 22nd district election last November to the Republican incumbent, Pete Olson, who derided him as an “Indo-American who is a carpetbagger” at a campaign event. But it was surprisingly close. In 2014, Olson’s margin of victory was 35 percentage points. In 2016 his lead was cut to 19 points. Last year it was sliced to only five points.

The district is now widely viewed as one of the most competitive in the country and Olson will not be on the ballot in 2020. He is one of four Texas Republican representatives in the space of less than two weeks who recently announced their retirements, including Will Hurd, the only black Republican in the House.

That three of them are in competitive districts adds fuel to Democratic hopes that Texas and its 38 electoral college votes, second only to California, will become a battleground state in local, state and presidential elections after decades as a Republican fortress.

Optimistic Democrats who backed O’Rourke’s bid to unseat senator Ted Cruz last year might argue that it already is up for grabs. Cruz clung on to his Senate job by just 2.6 percentage points in a contest that brought O’Rourke so much national attention that he decided to run for president.

In a district where a hundred languages are spoken, Kulkarni plans to redouble his campaign’s community outreach in 2020 after finding success reaching Asian American voters last year with a granular approach.

“People used to say that that would be a waste of time, a low ROI, because most people speak English or the people who don’t aren’t going to vote anyway,” he said.

“Now we’ve gotten them to come out in huge numbers. We can do the same thing with the Latino community which is one-fourth of this district but was the lowest turnout group among the four major ethnic groups. We don’t treat Latinos as a monolith, we go out into individual communities, whether you’re talking about a Honduran or Colombian or Venezuelan or Dominican immigrant community.”

“It’s not just about one candidate, it’s about all of these people saying ‘this does not represent me’,” Kulkarni said. “That’s why all these Republicans are retiring, because they don’t represent their communities.”