As Beto O'Rourke waited to address a large union gathering in Las Vegas, a campaign aide showed him the news that a gunman had killed multiple people during a mass shooting in El Paso, the city that raised him and the place he represented in Congress.

A stunned O'Rourke went into denial.

"I didn't believe it," he told The Dallas Morning News in an interview from El Paso. "Somebody showed me a tweet or text message. I said 'this is a false alarm.' That was my hopeful thinking. It wasn't something that my mind could accept."

Once reality set in, O'Rourke, visibly shaken, gave brief remarks at the union confab, then canceled all of his campaign events and headed home. En route, he checked in with his wife, Amy, who was returning home from a summer camp with their three kids. And he got more anxious as the casualties continued to rise.

"It just crushed me," he said.

Democratic presidential candidate Beto O'Rourke listened during a vigil at Ponder park in El Paso, Texas on Sunday, August 4, 2019. Less than a mile away is the scene where 20 people were shot and killed and 26 more were wounded at a Walmart in El Paso on Saturday. (Vernon Bryant/The Dallas Morning News) (Vernon Bryant / Staff Photographer)

As a candidate for Senate and now the White House, O'Rourke has held up El Paso as a national model, a diverse, safe city featuring a large bi-national community that's close-knit and unified, even with physical barriers along the border with Mexico.

O'Rourke has long maintained that El Paso — and Texas — could take the lead in rewriting the nation's obsolete immigration laws and show other cities that there's nothing to fear from immigrants.

So Saturday's shooting was not only an attack on O'Rourke's hometown, but also the El Paso way of life that's such a part of his political pitch to American voters.

O'Rourke said Monday that El Paso, now more than ever, is a symbol of the unity the country could achieve.

"I'm confident El Paso will be the example this country needs," O'Rourke said.

The former congressman, however, says the first step to bridging the nation's divide is getting President Donald Trump out of office.

O'Rourke has called the president a racist and forcefully denounced his rhetoric, from describing immigration from Mexico as an invasion or infestation to his comments that there were "very fine people on both sides" at a 2017 white supremacist rally in Charlottesville.

The Democrat continued his criticism of Trump on Monday, even as the president spoke out against racism.

"In one voice, our nation must condemn racism, bigotry and white supremacy. These sinister ideologies must be defeated," Trump said. "Hate has no place in America."

But O'Rourke says Trump is part of the problem.

"He's tried to make America fear immigrants," O'Rourke said, condemning what he called "racist and dehumanizing language" from the president.

"You do not get this shooter coming to El Paso until you have a president give him permission to do so," O'Rourke said.

Amid reports that Trump will visit El Paso on Wednesday, O'Rourke has said he doesn't think he should, saying the president played a role in the mass shooting.

While O'Rourke says Trump is the biggest concern, Republican leaders who back him — or don't speak out against him — are "complicit" in what occurred in El Paso.

"It's not enough to call it white nationalist terrorism," he said, adding that there are "too many voices that remain silent."

"What's necessary is to connect the dots to President Trump," O'Rourke said.

O'Rourke also criticized Texas leaders for pushing legislation that stoked fear and paranoia about immigrants, as well as those that support Trump's call for a border wall.

"It is not just Donald Trump. Many of our statewide elected officials in Texas have turned to Donald Trump's rhetoric and are trying to make us afraid of each other," O'Rourke said.

He added that the danger of anti-immigrant policies, including the state's sanctuary cities law that allows police to check the citizenship status of residents, has a chilling effect.

"You had people in the wake of the shooting who were afraid to seek care because they were worried that their immigration status would be used against them," O'Rourke said.

O'Rourke's anger at Trump, however, comes as he feels pride and admiration for the people of El Paso.

Iliani Ibarra of El Paso held up a sign as others held their phones during a vigil at Ponder park in El Paso, Texas on Sunday, August 4, 2019. Less than a mile away is the scene where 20 people were shot and killed and 26 more were wounded at a Walmart in El Paso on Saturday. (Vernon Bryant / Staff Photographer)

He said he was moved Sunday night by a prayer vigil for the victims of the massacre. He marveled at the courage of those injured in the shooting, watching them stay positive as their wounds were treated.

"It was one of the most beautiful things I've ever seen," O'Rourke said. "People are really coming together amid this horrible tragedy. ... They're so incredibly strong. They're just my heroes."

O'Rourke has halted his presidential campaign while he helps his hometown heal and said he hasn't thought about when he'll return to the trail.

"I haven't had these conversations yet with my team," he said. "I'm very focused on this community. I haven't made any plans to do anything else."

At least one media outlet has published a stinging criticism of O'Rourke's El Paso visit: The New York Post contended he was exploiting the situation for political gain.

O'Rourke said that was ridiculous and reiterated his passion for El Pasoans.

His tweet Saturday: "Love you, El Paso."

"There's nowhere in the world I'd rather be," he said Monday.