Why are the Trump defectors having such little impact on the polls and Trump's chances?

There are all kinds of things Trump’s base will excuse, as we’ve seen. The one thing that they probably wouldn’t excuse is Trump showing any signs of going soft or supporting any kind of liberal position. That’s why Trump always doubles down rather than admitting he messed up, regardless of what the issue is.

Which is why the question is, out of all Republicans, how many won’t care.

If you believe that “law and order” is the most important issue, then you’ll likely vote Trump. If you believe anything but law and order are the most important issues, then you likely won’t.

I don’t believe the situation is any more or less complicated than that at least at the moment.

I guess by “law and order” you mean “are upset about protests that get out of hand.”

I support law and I support order. I’m voting for Biden. Trump doesn’t encourage respect for the law and we have enjoyed much order under his watch.

For every complex problem there is an answer that is clear, simple, and wrong.
-H.L.Mencken.

I assume you mean “haven’t”.

But I agree - Democrats support law and order, which includes holding law enforcement accountable for breaking the law and ridding them of overtly racist practices that provoke social unrest. What Republicans support is authoritarianism, which is rarely lawful nor orderly.

I’m not at all defending the logic (in fact the seeming break down in social order is in my view largely because of Trump’s poor leadership) but to draw a comparison, after a disaster of a first time in office, Nixon won a landslide in '72 in part based on “law and order” support from “the silent majority”.

As a counter to that (and for some reason that '72 point has been repeated to death by many that listen to the right’s talking points) the Democrats did smart to that and very openly condemned the rioters and violence in 1992.

Republicans still did their damnedest to claim that Democrats where against law and order. The Bum, I mean, Bush senior lost the election. And I do think it was also in large part because it was very hard to miss the huge abuse police committed then to Rodney King on tape.

It may be a bit different now, but worse for the Republican president since he has been now treating the peaceful demonstrators, including mothers and grandmothers the same as the violent rioters; we also have even more tapes showing police abuse, and a president that also decided to get into the fray in the worst way.

“Law and order” has historically negative implications to the part of the population most disadvantaged. To them it seems that “order” takes precedence over “justice.” When the system is unfair to you, asking to wait quietly and work within the system for fairness seems awfully easy to expect if you’re not one of those adversely affected.