But why would they care if the border is closed if there's going to be a "guest worker program?" /rhetorical question
Because when these illegals become citizens, and even in the case of legal temporary workers, the law will require that businesses pay their FICA, minimum wage, vacation bennies, health bennies, family leave, retirement packages and so on and so forth. Those businesses will cut them loose and look for new illegals and new ways to scam the system.
Must be why he didn't say word one about enforcing the law on employers who hire illegals.