The entire Democrat party survival depends on importing millions of illegals and getting them into the voting system. Any threat to that strategy bring out an angry vile reaction.
The problem Democrats have is that even a good percentage of illegal immigrants eventually want to become citizens of the USA. They want their kids to be USA citizens. Then they actually pay taxes, SS, medicare. Then they realize that the Dems do not WANT people to improve themselves through hard work. They do not want Capitalists.