Actually if you look at leftist policy they don't think illegals should be deported even if they commit a crime, up to and including murder. Sanctuary city anyone.
I think this is how it went. Trump was pushing the we are going to build a wall and Mexico is going to pay for it. He got elected. Then he acted l ike he never lied and demanded U.S. pay for it and now. This made the Dems dig in and they could never ever give him one dollar for a wall. Not only did he lie, but then he turned the story against the Dems and his supporters did not even blink. Giving in $1 would destroy them for next election, especially after the shutdown. So the Dems, who previously had no issues with walls and border security, are suddenly shit on by Trump with no repercussions. and they were forced to run away in the opposite direction. Which leads us to this impasse that will never be solved really. Trump shut down the government and blamed the Dems and the Dems held on and survived so the last thing they will ever do in this term is let Trump declare he got a Wall built. That is the problem that started with just two incidents, calling those who cross rapists and murderers and then claiming Mexico will build a wall. GOP did not care as long as the Wall was built. Same GOP who sat on their ass for 2 years and distanced themselves from Trump until Dems won in 2018 which allowed them to then blame the Dems and remove the burden from their shoulders. The children play politics and nothing gets done.
After multiple examples along with this one, I think what people say of him as a 'master negotiator' or 'stable genius' is likely to be accurate.