It can be boiled down to this: political theater. That is because there is not an ice cube’s chance in hell that the GOP-controlled Senate would ever vote to convict.
The solution is to not ever get to the point of sending things to the Senate. Conveniently, impeachment is a lengthy process, lengthy enough that odds disfavor it being completed before the 2020 elections, anyhow. The point, to reiterate, is political theater: keep Trump’s high crimes and misdemeanors in the public eye, so that moderates and liberals feel motivated to turn out in November, 2020 and vote against Trump.
Congressional Democrats can’t openly admit as much, of course. They will have to claim they are just doing their Constitutional duty of oversight, and putting that well ahead of any political concerns. Well, welcome to the real world. Please, don’t tell me that professional politicians of all people suddenly have a case of aversion to telling convenient lies.
This gets to the flaw in the line of the reasoning the majority of congressional Democrats have, that weakness and capitulation are somehow virtues. They are not, and the fact that Democrats persistently tend to think they are is one of the reasons people don’t like Democrats. Democrats are seen as the party of weakness because they are by and large the party of weakness.
There is actually plenty of public support for progressive things like a wealth tax, a $15 minimum wage, and a green new deal. Contrary to the preachings of the so-called “moderate” wing of the Democratic Party, campaigning on such things is a recipe for success not failure. (Democrats tried choosing the “safe, moderate” presidential candidate in 2016; keep in mind what that accomplished for them.)
This doesn’t mean everything the left of the party wants is a winning idea. That same poll shows that campaigning for single-payer is basically a stupid idea. Solution: don’t do that. In addition to being unwise from a pragmatic point of view, and unwise from a concentration-of-power point of view, it’s simply not necessary.
But many left-of-center ideas are popular. A rotten, rigged system gives the right disproportionate power. Start acting like it, Democrats. Stop living in perpetual fear that Republicans won’t like you. News flash: they already don’t, and nothing other than going full Trump fascist is going to make them like you. Get over your stupid neurosis about not being loved by everybody and get busy adopting some principles and fighting for them.
Or get used to losing. Your choice.