Hi James:
Within your #4 lies the rub.

(Apologies to the Bard). Gallup, who most people respect, is showing a 6 point uptick in Trump's popularity since the impeachment inquiry began. https://news.gallup.com/poll/203207/trump-job-approval-weekly.aspx See also 538: https://projects.fivethirtyeight.com/trump-approval-ratings/
RCP average is about the same.
More than one polling outfit shows Trump polling with Blacks and Hispanics at historically high levels for an R.
Are these trends all pie-in-the-sky "malarkey?"
Maybe, but if these trends are real and they continue, it suggests a couple of things that Trump can and
is doing to change the situation, in some instances with a little help from Pelosi and Schiff or other Ds:
1. Continue to stoke, benefit from (and of course take credit for) a robust economy, whether one thinks this is deserved or not.
2. Continue to court the minority vote.
3. Effectively cast himself as the victim of an unfounded impeachment.
4. Be
twice the beneficiary of historically, legendarily, horrible D candidates who run historically, legendarily, bad campaigns.
Trump does not have a lot of control over #4, but he'll be hitting 1-3 and other factors hard as the campaign winds up. If those approve/disapprove lines in the Gallup poll (or the nearly identical 538 or RCP poll averages) cross, look for some serious panicking on the left.
Jim