Ms. Tamayo, who is on the Democratic primary ballot in El Paso on Tuesday and who voted for Ms. Warren for president, said that in knocking on doors for her campaign, she has seen firsthand a new level of engagement of Hispanic voters.

“We’ve been knocking on doors for more than three months, and I keep hearing that they want to vote in this election,” she said. “They really want to vote in this election because they feel like we’ve got to get Trump out of office. Instead of saying my vote doesn’t matter, I think people are now more willing to show up and more willing to vote because of that.”

Around El Paso, many people described similar reasons for voting: Mr. Trump’s rhetoric and the shooting last summer. But they came to different conclusions about their preferred candidates.

Anna Casas, 33, a single mother and home health aide in El Paso, voted for the first time in her life last week — her vote went to Mr. Sanders, and she had registered to vote last year about three months after the attack at the Walmart, where she would often shop with her three sons. “What about if we were there and that happened?” she said. “It did open my eyes. It pushed me to vote.”

Ms. Casas said it was clear to her that Mr. Trump’s words fueled the shooter’s hatred of Hispanics.

“I’m trying to push other people to vote, because they think that their vote doesn’t matter,” she said. “But it actually does. I used to think that way, honestly, until Trump became president.”

Irma Vasquez, 67, a former school-district worker who voted for Mr. Bloomberg, put the role the president’s words played in the attack this way, tugging at the skin on her cheek: “He put a bull’s-eye on our backs, especially this color.”

Pedro Gandara, 74, a retired telephone-company repairman and Air Force veteran who voted for Mr. Biden, said Mr. Trump evokes for him the anti-Latino racism he has faced his entire life. He remembered being refused service at a restaurant in the Panhandle city of Amarillo when he was a high school student.