"I think it contrasts very sharply with where Donald Trump has been on this issue," O'Brien told Jessica Rosenthal on Friday's "Fox News Rundown."
"We have had a wave of gun violence in the United States, a sharp escalation in hate crimes and domestic terrorism that are directly the result of, I think, the hateful language that Trump has deployed when he ran as a candidate and now as a president in an unwillingness to do the right thing on stemming gun violence."
The 60-second ad features Calandrian Simpson Kemp, a Texas woman whose 20-year-old son, George Kemp Jr., was shot and killed in 2013. The issue has been a centerpiece of Bloomberg's campaign. The former New York City mayor is also a founder and major financial supporter of the nonprofit Everytown for Gun Safety, which advocates for greater gun control.
"This is something that touches families," O'Brien explained. "It most profoundly touches communities of color. Some of the most vulnerable communities in our country -- it's in our schools. It's where people pray. And we can't say we're a civilized country if our kids have to hide under their desks or worry about hiding under their desks because there's an active shooter in a school."
With the Iowa caucuses four days away, O'Brien also addressed the Bloomberg campaign's decision to skip the early-state nominating contests and focus instead on the states that award their delegates on March 3, a date known as Super Tuesday.
"We have a national footprint right now in over 35 states with about a thousand people on the ground. We're running three campaigns simultaneously," he explained. "Essentially, we're running a general election campaign right out of the gates against Donald Trump.
"We're also running, obviously, a primary campaign that really hinges on Super Tuesday states as our first showing. And we're also prioritizing a handful of battleground states where we think the 2020 election is going to be won or lost."
Bloomberg has struggled to gain support among people of color, in large part due to the controversial “stop-and-frisk” policy he implemented during his time as mayor of New York. In November, Bloomberg apologized for the policy, saying, "I was wrong."
O'Brien said the campaign will "continue to apologize" for the policy and that the candidate is "pained" by the idea that it was driven by racist motivations.
"I think his goal was to reduce gun violence on the streets," he said. "But the program and that approach was a mistake. He's apologized for it ... and I think it's a measure of his self-confidence and openness as a candidate that he can apologize for his mistakes. Having said that, stop-and-frisk hardly defines his tenure as mayor of New York. He lowered the incarceration rate by over 34 percent ... So 'stop-and-frisk' was not about throwing people in jail."
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