Though obviously the reality of illegal immigration policies and enforcement over the past few decades has been rather more nuanced and less 'Left v Right' than the political rhetoric about it in election campaigns on both sides - for instance, the big bipartisan immigration reform proposal of the 'Gang of Eight' back in 2013 (which I was reminded just now included Marco Rubio as a cosponsor), which passed the Senate with a large bipartisan majority though the Republicans blocked it in the House.

But as for how the US got Trump administrations as opposed to Republican ones, and this utter degradation beyond repair of the Republican party, the Republicans only have themselves/their voters to blame for that.