Let's take maximum long run advantage of the current tsunami of anger and shock at the Trump victory, that is so widespread.
With 2018 (and 2020) in mind, the Democratic party should right now start a ferociously strong registration drive aimed at groups that leaned Democratic in 2016 but did not vote.
We Kossacks can play a very strong role by asking friends and friendly acquaintances whether they are upset by the election of Trump, and if yes, push them to act now to help neutralize Trump in 2018 — by registering if they are not currently registered; by committing to vote Democratic, even for candidates they are not excited about (in order to win control of Congress); by pushing others who dislike Trump to do likewise.
This is a very good time to start organizing massive voter registration to elect Democrats to Congress and to state houses and to cities and municipalities for 2018. And for the next presidential, in 2020. This is the best way to resist Trump.
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P.S. In my own family circle, which is almost uniformly progressive, there was extreme upset at Trump’s election. My wife did not even want to talk, she was so devastated. But outside my family, I have been astounded at the intense negative emotional response of many people I know to the election of Trump, including people who normally take little interest in politics. Some of them cried, or reported friends who cried, or were angry, or were frightened. A predominant question was “How could this have happened?” I have not seen this kind of response in any previous elections. I think that if properly handled, this could easily tip the midterms.