Believe it or not, I had considered saying Alexandria Ocasio-Cortez is the worst representative in Congress, and I do think she comes close, but Steve King has ties to the white nationalist movement that I can't stand.
I do also think Ilhan Omar is awful. What she said about the Jews and Israel, and later referring to 9/11 as "some people did something" is inexcusable. Rashida Tlaib is also pretty bad when you consider the type of language she uses.