Trump doesn’t have to do much arm-bending with LEO. He simply has to start enforcing laws already on the books.
The thin blue line will. The political law enforcement powers that be will follow the power of money.
I work in probably sanctuary city number one, San Francisco, and I don’t see this as a huge problem for Trump, He can start with voluntary cooperatives, which will be all but about 50. Then proceed to those cities located in states with Republican governors and/or legislature’s. That will leave about five cities, Examples should be made out of them, with every crime perpetrated by an illegal alien plastered all over Trump’s Twitter account, right.wing media etc., not mention cutting off their federal funding, They’ll cry uncle pretty quickly.