Do you actually believe there are radical leftists in the US Congress?

There are some very left-wing people in Congress -- namely The Squad and Bernie Sanders -- but I wouldn't go so far as to say radicals. To me, radicals are people who are so extreme that their visions for the world would completely restructure society, to the point where it's barely recognizable to us, like a Nazi, Communist, or anarchist. None of the leftists in Congress really want to do that (though they do seek great change). They just want to adjust the systems we have -- such as tax law, Medicare, the public education system, etc. to perform new functions.