The opening hour of the Democrats’ all-virtual convention featured several nationally recognized politicians addressing topics like systemic racism, police violence and economic recovery.

But some of the most striking comments came from a woman few Americans may have heard of before Monday.

That speaker, Kristin Urquiza, whose father died this summer in Arizona, opened her brief but impassioned speech bluntly: “I’m one of the many who have lost a loved one to Covid,” she said. “My dad, Mark Anthony Urquiza, should be here today, but he isn’t.”

The reason, she asserted, was President Trump.

“My dad was a healthy 65-year-old,” she said. “His only pre-existing condition was trusting Donald Trump — and for that he paid with his life.”

Ms. Urquiza garnered attention this year when she wrote an obituary published in The Arizona Republic in which she laid blame for her father’s death at the feet of state and federal leaders and their handling of the coronavirus pandemic.

On Monday, she walked through her thinking for a national television audience, saying that her father had voted for Mr. Trump, had “had faith” in him, and had believed it would be O.K. to go to a karaoke bar soon after Arizona’s stay-at-home order had been lifted.

Speaking as pictures of her father flashed across the screen, Ms. Urquiza said he had “died alone, in the I.C.U., with a nurse holding his hand.”

“Donald Trump may not have caused the coronavirus, but his dishonesty and his irresponsible actions made it so much worse,” she said.

“One of the last things that my father said to me was that he felt betrayed by the likes of Donald Trump,” she added. “And so when I cast my vote for Joe Biden, I will do it for my dad.”

Here is a rough transcript of her remarks:

Kristin Urquiza: Hi. I’m Kristin Urquiza. I’m one of the many who have lost a loved one to Covid. My dad, Mark Anthony Urquiza, should be here today, but he isn’t. He had faith in Donald Trump. He voted for him, listened to him, believed him and his mouthpieces when they said that coronavirus was under control and going to disappear, that it was O.K. to end social distancing rules before it was safe, and that if you had no underlying health conditions you’d probably be fine.

So in late May, after the stay-at-home order was lifted in Arizona, my dad went to a karaoke bar with his friends. A few weeks later he was on a ventilator, and after five days he died alone, in the I.C.U., with a nurse holding his hand. My dad was a healthy 65-year-old. His only pre-existing condition was trusting Donald Trump — and for that he paid with his life.

I am not alone. Once I told my story, a lot of people reached out to me to share theirs. They asked me to help keep the community safe, especially communities of color, which have been disproportionately affected. They asked me, a normal person, to help, because Donald Trump won’t.

The coronavirus has made it clear that there are two Americas: The America that Donald Trump lives in and the America that my father died in. Enough is enough. Donald Trump may not have caused the coronavirus, but his dishonesty and his irresponsible actions made it so much worse.

We need a leader who has a national, coordinated, data-driven response to stop the pandemic from claiming more lives and safely reopen the country. We need a leader who will step in on day one and do his job: to care.

One of the last things that my father said to me was that he felt betrayed by the likes of Donald Trump. And so when I cast my vote for Joe Biden, I will do it for my dad.