It now feels quaint that, not long ago, people used to speculate what Gödel's loophole was:
https://en.wikipedia.org/wiki/Gödel%27s_Loophole
We're witnessing that there doesn't need to be any single clever actively exploited loophole. A two-party presidential system can become a dictatorship if one party holds just enough power across all branches of government to not resist what their leader wants.