People are going to believe what they want. Trump is still getting strong support from farmers even though they are losing money from his tariff war and may face greater losses in the future when their foreign markets have gone elsewhere:
https://www.cnn.com/interactive/2018/politics/kitchen-table-election/index.html

They economy is slowing from the early growth due to tax cuts as the tariffs are raising prices and slowing sales. The growth in the last quarter was weak compared to last year and down significantly compared to last year and the previous quarter. However this isn't going to convince voters that Trump's bad for the US economy because the worst effects won't hit until after the election. Voters will believe Trump's lie about Congress passing a middle class tax cut before the election even though Congress is in recess until after the election and can't vote.

This election is a Halloween scare the voter and see who does a better job at it.

I feel theres a strange disconnect between how much Trump is hated and by how job numbers look. Its hard to argue the economy is collapsing. Its even harder to argue the tax cuts havent improved the economy. Is this midterm just going to be a befuddled repudiation of a dying morality of the Republican-anything-for-money-mentality