One way, there are four (4) Congrassional seats up for special elections in the near future.  For each one of these, we have to encourage that strong Democrats be selected to run.  Then, we have to support them with strong Get Out The Vote efforts.

BUT MOST IMPORTANTLY, we have to go to the polls and vote.  When Republicans see that supporting Trump will cause them to lose their reelection in 2018.  They will change.