To be the smartest person in the room the next time this subject is broached, read this:

Blinder and Watson at Princeton published a paper in 2015 documenting the very real phenomenon.

https://www.aeaweb.org/articles?id=10.1257/aer.20140913

I recommend dl the .pdf, it's the final authority on the topic.

Abstract

The US economy has performed better when the president of the United States is a Democrat rather than a Republican, almost regardless of how one measures performance. For many measures, including real GDP growth (our focus), the performance gap is large and significant. This paper asks why. The answer is not found in technical time series matters nor in systematically more expansionary monetary or fiscal policy under Democrats. Rather, it appears that the Democratic edge stems mainly from more benign oil shocks, superior total factor productivity (TFP) performance, a more favorable international environment, and perhaps more optimistic consumer expectations about the near-term future. (JEL D72, E23, E32, E65, N12, N42)