Every time I try playing with the U.S. I’m always assassinated by the black power group about halfway through the term or less. As the U.S. you start off already with a lot of racial tension due to immigration and ethnic minorities opinions are very low due to issues with ghettos, so is this just me playing badly or is it something due to the setup? One time I wasn’t assassinated by them, but was instead assassinated by the capitalists. I’ve yet to be assassinated in any other country than the U.S., and for some reason I’m consistently getting over 90% of the vote in Germany. So I’m not really sure 
How is the crime and poverty situation? You should be able to get by just fine with immigration at any level, as long as there isn’t also poverty, unemployment and crime. The USA is a harder country in the game than some of the others, but it’s definitely winnable :D.