Exactly. Trump's core base is as solid as it gets. It's looking like the same may be said of the Dems (hopefully). But both sides need Indies, to prevail. I suspect most Indies have strong leanings, but I'm also sure some do indeed move. Keep whittling away at a half-a-point here, a-half-a-point there, and you can move elections.
According to the aggregate average at 538.com, over the past ten days Trump's approval-disapproval gap has grown by a solid 3 pts. The pace especially accelerated the past few days. This coincides with Trump refusing to honor his Congressional subpoenas. It is my belief the change has been due to Trump's obstructing behaviour.
Let the Dems keep it up, and see what happens. It's just been announced there is going to be a full House vote tomorrow to issue a resolution-of--official-investigation against Trump. If it passes, I assume it will, it will not just give additional political gravitas in the current investigations, but most importantly it opens up much stronger legal avenues for subpoena.
The SCOTUS has historically stood rock solid behind the House's subpoena rights in official misconduct investigations, and indeed they fast-track them due to it being an official inquiry. This is what occurred with Nixon. It was less than two months from the first lower court subpoena appeal by Nixon, until he was ordered by SCOTUS to immediately release the tapes (he resigned two weeks later). Those two months included all appeals, motions, arguments, directives, deliberation - everything!
One more thing: Starting an official inquiry places more pressure on Mueller to show for a public hearing. It virtually compels him to action (IMO).
