Princeton economist Alan Blinder wrote an op-ed in the NY Times recently describing a new study that showed income inquality increasing during Republican administrations and decreasing during Democratic adminstrations. This pattern goes back for the last 60 years. The study also notes that the economy has grown faster under Democrats during the same 60 year period.
Although Blinder has worked in Democratic administrations, he is a big deal economist. His textbook Economics: Principles and Policy, written with William Baumol, is a classic, which I used as an economics major in college.