Effective opposition contains three components. First, you have to take positions on the issues that will get you elected; second, you have to take actions while in office to check Trump’s excesses; and third, you have to mobilize public support for guardrails against the abuse of executive power.
What effective opposition does not consist of is taking positions that are unpopular and unrealistic, going off on personal safaris that divide the Democratic Party, and making loud and controversial statements on social media that alienate potential swing voters. In other words, the Democrats do not need their own version of the Tea Party; they are the party of responsible adults and stable government, not a flock of sheep or a collection of noisy narcissists.