He respectfully dispatched a question from a woman in the crowd from an anti-illegal immigration group, who arrived with others who appeared looking for confrontation. The woman called him by his given name, Robert, and asked why he was "pandering to illegal aliens" over those who came to the U.S. legally.

"Second," she said. "Hands off our guns, Beto."

The crowd chanted her down while O'Rourke responded by saying in part, "What is a slap in the face to my conscience and the best traditions of this country is taking kids from their parents and putting them in cages." His closing response to her: "Those immigrants pose no threat to you."

In an interview with The Arizona Republic's political podcast, "The Gaggle," O'Rourke said Trump must be held accountable for urging Ukrainian President Volodymyr Zelensky to open an investigation into former Vice President Joe Biden's son Hunter Biden. Asking a foreign country to intervene in U.S. politics, along with allegations that American aid may have been tied to the request, have sparked an impeachment inquiry.

"Here's the challenge for Americans ... if we allow this to stand without accountability, we will have set the precedent that some people are above the law in this country," he said. "And the moment that we accept that is the moment that we lose this democracy for everyone. So this is a moment where we ask everyone to put country before party, country before their own political careers and do the right thing while we still have time."