Republican presidential candidate Donald Trump points to supporters during the opening session of the Western Conservative Summit in Denver on July 1. (David Zalubowski/AP)

Update: In perhaps the most telling example of Trump's tendency to turn attacks that have been used against him on his opponents, on Wednesday night Trump called Hillary Clinton a "bigot." This is a label, of course, that Trump critics have slapped on him basically since he launched his campaign.

Below is a post from earlier this month that explored this pattern of Trump attacking Clinton for things he has also been attacked for, including his temperament and mental stability.

Last week, the speculation over Donald Trump's mental health kicked into high gear. MSNBC host Joe Scarborough asked whether Trump was a "sociopath." A former Harvard Medical School dean said Trump was the very definition of narcissistic personality disorder. A Democratic congressman called him "mentally unstable." Mark Cuban called him "bats--- crazy." Dr. Drew even weighed in because ... well, Dr. Drew. And the American Psychiatric Association even saw fit to remind its members that they shouldn't be diagnosing Trump from afar.

Trump's response? Pull the "unstable" label off himself and slap it on his opponent.

The Republican nominee spent much of the weekend arguing that it is actually Hillary Clinton who is mentally ill — not him. Call it Trump's (to borrow a playground retort) "I know you are, but what am I" strategy.

On Friday, he told a Des Moines crowd that Clinton was "pretty close to unhinged, and you've seen it. ... She's like an unbalanced person."

He pushed even harder over the weekend. "Honestly, I don't think she's all there," Trump said Saturday night in New Hampshire. "She took a short-circuit in the brain," he added. He also called her "unstable," "unbalanced" and "totally unhinged."

And he tweeted this:

Trump does this often. He'll be attacked for one thing or another and look to muddy the waters by arguing the same thing applies to someone else — usually Clinton. It's completely transparent in its simplicity and brazenness.

For example, poll after poll has shown that the vast majority of Americans don't view Trump as being qualified to be president. Trump's response? Argue that Clinton isn't qualified.

In fact, the morning after Clinton herself said Trump isn't qualified, on May 19, Trump basically said (to borrow another playground quote), "I am rubber and you are glue; whatever you say bounces off of me and sticks to you."

And he has kept up the attack ever since.

Polls also show the vast majority of Americans don't think Trump has the temperament to be president. A Washington Post-ABC News poll in late May showed 70 percent said Trump doesn't have the right kind of temperament to be president. Clinton has called Trump "temperamentally unfit" to be president.

So Trump now suggests it's Clinton who doesn't have the temperament — over and over.

"I have a winning temperament," he said last week. "She has a bad temperament. She's weak."

"She lacks the temperament," he said Saturday night.

"Hillary Clinton wants to be president," he said June 22. "But she doesn't have the temperament."

Trump has also endured months of attacks arguing that he and/or his policies are racist — particularly when it came to his comments about a judge of Mexican descent. So when Trump feuded with Sen. Elizabeth Warren (D-Mass.), he said it was Warren who was the racist. Twice.

And after Democrats a couple weeks back raised concerns about Trump's receiving classified national security briefings, Trump responded the next day as you might expect.

Trump's effort in this regard has become completely transparent in recent days. But it's something that one person who has worked closely with Trump says he has long noticed.

Tony Schwartz, who ghostwrote Trump's "The Art of the Deal" and has been an extremely vocal Trump critic of late, tweeted a couple weeks back that Trump's criticisms of others are usually more about himself.

Schwartz re-upped the theory over the weekend, after Trump attacked Clinton's mental stability.

The political strategy here makes sense — at least in theory. Trump is trying to turn his worst negatives into negatives for his opponent. If people don't think he's qualified to be president and doesn't have the temperament, the best way to mitigate the damage is to give people the same reservations about Clinton.

This is an old campaign strategy; Trump is just more shameless about it.

But the corollary to that rule is: If an attack doesn't fit into a preexisting narrative, it's a tougher sell. "Crooked Hillary" builds on two decades of attacks on Clinton's character; a "Crazy Hillary" story line does not. And unfortunately for Trump, it doesn't appear to be paying dividends. No matter how much he criticizes Clinton's fitness for the job or her temperament, people just aren't buying it. A new Washington Post-ABC News poll shows 60 percent of people think Clinton is qualified to be president vs. 38 percent who say the same of Trump. Similarly, 61 percent say Clinton "has the kind of personality and temperament it takes to serve effectively as president," while just 31 percent say that applies to Trump.

Her numbers on both of these questions are basically unchanged in recent months.

It seems this strategy works less well once you graduate beyond the playground.