“don’t see how the Democrat reverses this.”
No need to win in some kind of abstract mathematical thing like vote counts (which must be discounted as inherently racist and transphobic if the Democrat loses).
The Democrat victory is inevitable in the re-telling, and in the minds of the faithful.
The story will be that the Democrat “outperfomed”, and that therefore the Republicans are doomed in the midterms, unless they reject and stymie every effort that Trump proposes. This election will clearly prove to them (regardless of results) that the public now decisively rejects Trump.
....or they’ll invoke the Russians. Don’t doubt me on this! :)