The Dems need to make the case for the need for a Dem Senate. They need to go for a full tidal wave landslide.
This is where the Dems could use Soros/Bloomberg PAC money and make very targeted consisent and coherent attacks against the complicity and cowardice of Senate Repubs in empowering and refusing to question an inept authoritarian dangerous nut-job like Trump.
The Blue Tsunami may hit the US shore hard this year but when waters retreat in the out years and the damage done by the Trump-Repubs become glaringly obvious, its going to up to the Dems to clean up the Repub mess, so they're the ones who will get dirty.
But Repubs will then blame Dems for a slow clean up effort. And that they have the answers to right the ship, hello 2022 off-year elections!
So Dems basically have to run-up the score in 2020, and neuter as many Repubs as possible, gain the WH, House and Senate, clean up the disaster, feeding the hungry, heal the sick, and put together a sane package (maybe infrastructure-jobs, expanded heathcare, continued government support for an ongoing economic recovery, rebuilding US stature with traditional allies,) that doesn't scare mod and indy voters in 2022. Stay the fuck away from medicare for all and soaking the rich and corps in taxes, hold-off on controversial, divisive stuff, as Dems will need time and consensus to rebuild America, and there will be pain and costs to be borne and likely by those that have disproportionately and unfairly benefitted over the past 40 or so years.