“Obama-Clinton have single-handedly destabilized the Middle East, handed Iraq, Libya and Syria to Isis, and allowed our personnel to be slaughtered at Benghazi,” Trump wrote, in a single-paragraph release sent to reporters by his campaign. “Then they put Iran on the path to nuclear weapons. Then they allowed dozens of veterans to die waiting for medical care that never came. Hillary Clinton put the whole country at risk with her illegal email server, deleted evidence of her crime, and lied repeatedly about her conduct with endangered us all. They released criminal aliens into our country who killed one innocent American after another... and have repeatedly admitted migrants later implicated in terrorism.”

“They have produced the worst recovery since the Great Depression,” Trump continued. “They have shipped millions of our best jobs overseas to appease their global special interests. They have betrayed our security and our workers, and Hillary Clinton has proven herself unfit to serve in any government office.”

During the primary season, as Donald Trump’s bizarre outbursts helped him crush the competition, I thought he was being crazy like a fox. Now I am increasingly convinced that he’s just plain crazy.

I’m serious about that. Leave aside for the moment Trump’s policies, which in my opinion range from the unconstitutional to the un-American to the potentially catastrophic. At this point, it would be irresponsible to ignore the fact that Trump’s grasp on reality appears to be tenuous at best.

Begin with the fact that he lies the way other people breathe. Telling a self-serving lie — no matter how transparent, no matter how easily disproved — seems to be a reflex for him. Look at the things he has said in just the past week.

Critics believe that in the case of the Khans, Trump has gone way too far, comparing it to a famed turning point for McCarthyism in the 1950s. Grilled by then-Sen. Joseph R. McCarthy at a congressional hearing as part of the Wisconsin Republican’s crusade to root out communist sympathizers, then-Army counsel Joseph N. Welch asked, “Have you no sense of decency, sir? At long last, have you left no sense of decency?”

Initial reports suggest the Khan episode has hurt Trump, at least for now. A pair of national polls taken over the weekend and released Monday showed a ­sizable bump for Clinton, suggesting the Khan affair, coupled with a successful Democratic convention, was working to her advantage. Clinton led 52 percent to 43 percent in a CNN-ORC survey and 47 percent to 41 percent in a CBS News survey.

Polls consistently show that Trump’s biggest vulnerabilities are on questions of character and temperament. Three-quarters of Americans said Trump does not show enough respect for people he disagrees with, and 55 percent said this was a “major problem,” according to a Washington Post-ABC News poll in May.

...

Democratic strategist Stephanie Cutter, a former adviser to Obama, said Trump’s comments about the Khans are breaking through to voters because they violate people’s expectations of decency and empathy.

“They worry about what kind of role model this sets for their kids,” Cutter said. “They don’t want a president who is insulting people based on their disability or religion or gender or threatening to knock somebody in the head.”