Regarding the CNN poll, here's a couple of points to keep in mind:
1) 36% more people described themselves as Dems than Reps.
2) 78% of the Dems think Trump is handling the economy poorly.
Record economy is poor because it makes the Dems look bad.
http://cdn.cnn.com/cnn/2018/images/09/10/rel8a.-.trump.pdf