"Trump is bad." That's basically all you need for 2016.
FTFY. You need something more than "Trump sucks". You need a vision.
Not during the midterms you don't, midterms are almost always about accentuating the negative of the current administration. That being said, I think it would benefit the Democrats to focus on message tweaking and crafting a broader narrative as a long-term strategy, but if Trump has royally screwed the pooch by 2018, reminding the public how the the Trump administration is in bad need of a power check can carry the Democrats pretty far.
