That's one thing he's very good at, I've found.
The open borders guys are the ones promoting the agenda of racists, specifically the Movimiento Estudiantil Chicano de Aztlan, or MEChA, which stands for the Chicano Student Movement of Aztlan. Their motto is "Por La Raza todo. Fuera de La Raza nada (For the Race, everything. For those outside the Race, nothing)."