Vanessa Williamson of Brookings has a good piece out on their website about the political effects (or lack thereof) of Trump's tax cut. This is a solid article which, in passing, concisely and fairly summarizes a lot of the political science research relevant to this issue. Recommended, though I guess I'm less sure Democrats could make a big issue of this even if they wanted to. Perhaps they should be satisfied with the fail of the issue for the GOP.
Her general conclusion:
"[T]here are only a few avenues by which the legislation is likely to help Republican chances. It is deeply implausible that voters will behave differently due to the very small changes the TCJA made in their individual take-home pay. The legislation is also poorly situated to mobilize Republican voters, whose support for the legislation was lukewarm. The short-term stimulative effects of the TCJA are also unlikely to matter much, both because the effects are small and because the economy matters less for midterm election results. In the longer term, however, Republicans will likely benefit from the law’s upward redistribution targeted to their donor class."