It was Ted Kennedy, IIRC, who went back on his word to Reagan that he and the Senate would abide by it. I could be wrong about it, but that’s what sticks in my mind.
There is some rose colored glasses about Reagan and illegal immigration on FR.
Here he is in 1980 against the Wall and advocating for open borders.
https://youtu.be/YsmgPp_nlok?t=92