Is there any doubt?
It is the single reason that we have so much illegal immigration from the south, and the single reason that stops Congress from immigration reform, as republicans are lining their pockets from these lobbies and their masters. Dubya wanted to do it, and his party stopped him.
It also is the single reason they are not in jail.
The Democrat party should make it a platform issue that “we will stop illegal immigration at its ROOT”.
It is much cheaper than building stupid walls, to begin with.