Working paper points to "systematic bias against liberal policies at a state level".
If this working paper holds up under further research, then the idea that the US is a "center-right" country is false.
Broockman and Skovron find that legislators consistently believe their constituents are more conservative than they actually are. This includes Republicans and Democrats, liberals and conservatives. But conservative legislators generally overestimate the conservatism of their constituents by 20 points. “This difference is so large that nearly half of conservative politicians appear to believe that they represent a district that is more conservative on these issues than is the most conservative district in the entire country,” Broockman and Skovron write. This finding held up across a range of issues.
My bold. This is really worth reading, short and interesting. If you've ever felt that the conservative media has created a fantasy world, this is strong evidence that that's exactly what's happened in the US.