Pretty much everything Rich writes below is reasonable. And I think his concluding paragraph is entirely fair:
Anyway, I believe the simplest explanation for most Trump controversies is that he’s being crude and thoughtless, and that applies here. The sh**house controversy has been longer-lasting than most, now on its fifth day, but by the end of week, we’ll be on to something else.
Except for one thing: It’s not entirely clear to me that Trump was being “thoughtless.” He may have made a bad calculation. There are only two possibilities. The first is that he thought the comments wouldn’t be leaked — a bizarre notion, not just because there’s so much leaking from this White House, but particularly because Dick Durbin was in the room. The other option is that he knew it would get out.
The second scenario is more likely. Indeed, there are reports that Trump thought his sh**house comment was good politics, which he all too often defines as pleasing his base. As I wrote about in last week’s G-File, an obsession with pleasing your base at all costs is a somewhat novel theory of presidential politics and even presidential conduct.
As a practical matter, not everything Trump does that revs up his base is bad policy or bad politics. But they very often are — either on the merits or due to poor messaging. In particular, episodes like the sh**house controversy unite Democrats and most independents against the White House and the GOP, and they divide Republicans. Indeed, the Republicans in the room are now themselves struggling to get on the same page about both policy and their accounts of what happened. Conservative pundits and politicians are scrambling to find a coherent and plausible way to defend a statement that was unwise, either as a matter of decency or practical politics (or both).
This is a small example of the larger trend. It’s not exactly a new insight that successful presidents come up with issues that divide the opposition and unite their own coalition. That’s why Democrats whined for decades about “wedge issues.” The ideal issue for any politician is what some people call a “70-30” issue, if the politician can claim the 70 percent side. Trump plays the politics of wedge issues all the time, but he tends to take the 30 percent issues that divide Republicans and enlarge the opposition. Whether he’s right or can, with great effort, be defended on a specific controversy doesn’t change the fact that Trump has a gift for making the jobs of Republicans harder and the jobs of Democrats easier.