Trump has built his campaign partly around calling for cracking down on immigration and the southern border, even endorsing using police and the military to carry out mass deportations should he be elected in November. At nearly all of his campaign rallies, the Republican former president scoffs at Democrat Harris as a former Biden administration “border czar,” arguing that she oversaw softer federal policies that allowed millions of people into the country illegally.

President Joe Biden tasked Harris with working to address the root causes of immigration patterns that have caused many people fleeing violence and drug gangs in Central America to head to the U.S. border and seek asylum, though she was not called border czar.

Since taking over for Biden at the top of the Democratic presidential ticket, Harris has leaned into her experience as a former attorney general of California, saying that she frequently visited the border and prosecuted drug- and people-smuggling gangs in that post. As she campaigns around the country, the vice president has also frequently criticized top Republicans for voting down a sweeping, bipartisan immigration package in Congress earlier this year after Trump opposed it.

Harris has worked to make immigration an issue that can help her win supporters, saying that Trump would rather play politics with the issue than seek solutions, while also promising more humane treatment of immigrants should she win the White House.