Obviously they don't want to close the US-Mexican Border! And they have done everything possible to prevent President Trump from saving the American People from such violent criminals.
Why do they want to import these subhumans?
Because they expect them to become pro-Democrat voters.
Also the Cartels have plenty of money to donate to Democrat politicians.
Why would Democrats not cultivate such thugs? After all, the Democrat Party is the Party of Evil. It has a long, ugly history, from slavery, to the ku klux klan, to infanticide, coup d'état, lynching (both high and low tech), satanism, witchcraft, framing the innocent for nonexistent crimes... What's heroin and cocaine pushing, human trafficking, and drug related massacres after a history like that?
The Democrat Party is the Party of Hate, Violence, and Evil. Of course it supports the Drug Cartels.
The USSR used these types as Enforcers and to keep what there was of a middle class off balance. They were the rulers in the prison camps. Communists label violet criminals as Social Allies.