This Huffington Post piece explores why the Clinton camp isn't going after Donald Trump for his notorious policy "flip-flops."
Part of the reason is the erratic nature of Trump’s policy pronouncements. As one top Clinton aide explained to The Huffington Post, it’s difficult to attack the GOP nominee for flip-flopping if, ultimately, he ends up at the very same position where he started. [...]
But the main reason the Clinton camp has kept the “flip-flopper” charge on the shelf is because their research shows that voters respond better to the idea that Trump’s motives are subconscious, rather than political.
That may be overcomplicating things. A simpler rationale would be this: There's no need to. The Clinton campaign has largely stayed out of Trump's way, while Trump tools around the country making one ridiculous claim after another, because Trump is doing a remarkably effective job of disemboweling himself during those appearances. He contradicts himself on a regular basis—but the media is already all over it. He says racist and sexist things—and those things are reported. He lies outright—but an increasingly irritated media is beginning to call that out, too.
We may be in the general election now, but Donald Trump is still running a campaign aimed firmly at his base of hard-right racists and xenophobes, and there is absolutely no reason why the Clinton camp would want to interrupt him. Clinton almost never engages Trump directly, but instead is continuing the positive we-can-do-better messaging of the Democratic convention. She has given a few speeches slamming particular aspects of Trump's policy stances and demeanor, and that's been sufficient.
There's no need to point out to voters that Trump is erratic, incoherent, foolish, narcissistic, inexperienced, radical, xenophobic, aggressive, insulting, bombastic, or stupid. Polls show voters are already quite aware of it, so Clinton can stay far above the fray and look, in contrast to Trump, presidential.
As for whether or not the "flip-flop" label will ever be hauled out to attack Trump, in future months? It's not likely. "Flip-flopping" is something you pin on a career politician for changing policy positions for political expediency: It's an argument that speaks to an established politician's sincerity, but presumes their competence.
The measure being taken of Trump, on the other hand, is not of his sincerity but his sanity. Donald Trump would have to become three times the man he currently is before attacking the individual bits and nuances of his currently batshit-insane declarations and pronouncements made electoral sense. Treating his radical stances seriously would only serve to legitimize them; doing so would be exactly the last thing the Clinton campaign would want to willingly do.