Less than 200 miles from the southern border, Vice President Kamala Harris promised to fight for “strong border security,” going after Donald Trump for killing immigration legislation that would have curtailed asylum and promising to sign such a bill into law if elected.

“I was attorney general of a border state. I went after the transnational gangs, the drug cartels and the human traffickers,” Harris said, touching on an issue she has rarely spoken about in depth. “I prosecuted them in case after case and I won, so I know what I’m talking about.”

Speaking in front of a crowd of more than 15,000 supporters at the Desert Diamond Arena, Harris blamed Trump for the failure of Congress to pass a bipartisan border deal earlier this year: “He talks a big game about border security but he does not walk the walk,” Harris said to a raucous Sun Belt crowd.