What should the Democratic 2020 main campaign message be?

I went with negative for the reasons I gave in the portion quoted below to another thread.

Also, there is no way that any of the “positive” campaign promises included in a positive Democratic message will actually be achievable. At best there will be a small majority in the Senate patched together with Centrist Democrats from Red states who will flee in terror from any step outside of the box, or more likely a turtled up Mitch who would like nothing better than the complete destruction of health and prosperity in the US, provided a Democrat is in charge at the time.