Donald Trump Is 'Off His Rocker': President's 'Alarming' Rob Reiner Post Has White House Insiders Questioning His Sanity, Claims Biographer

Donald Trump has rubbed many the wrong way after his unhinged post about Rob Reiner's tragic death went viral.

The 79-year-old president’s wildly insensitive remarks on Monday, December 15, even have loyalists within the White House on edge, according to Trump biographer Michael Wolff.

During an appearance on the "Inside Trump's Head" podcast on Tuesday, December 16, Wolff dished that a White House source told him, "I don’t know what that was, but it wasn’t good. Everybody knows it’s a thin line he walks. Is he teetering? Well..."

The show's co-host Joanna Coles responded, "Well, I wouldn’t say it was teetering, I would say it’s fallen off the line."

Wolff went on to say, "We all become kind of diagnosticians of these old-man presidents. I mean, nobody is going to come out and say, 'He’s losing it.' So we all have to make our own judgments about that."

The writer continued, "And I think in this situation, particularly in this situation — in the way that everyone who has a family at some level relates to this — I think the judgment is going to be a devastating one: Trump is off his f------- rocker."

In his Truth Social post, Trump called Reiner — whose drug addict son allegedly murdered him and his wife, Michele Singer Reiner — a "tortured and struggling" director who died "due to the anger he caused others through his massive, unyielding, and incurable affliction with a mind crippling disease known as TRUMP DERANGEMENT SYNDROME."

The divisive POTUS added that Reiner was supposedly "known to have driven people CRAZY" with his Trump "obsession."

The When Harry Met Sally director was outspoken about his hatred for the president.

When questioned about his statement during an Oval Office press conference on Monday, Trump doubled down on the scathing post.

"I wasn’t a fan of his at all," he bluntly told reporters. "He was a deranged person."

He further added, "I thought he was very bad for our country."

Rob, 78, and Michele, 68, were found with knife wounds inside their Los Angeles mansion on Sunday, December 14.

As OK! previously reported, their daughter Romy discovered her father's body and paramedics later informed the 28-year-old that her mother was also dead.

Their troubled son Nick, 32, has since been formally charged with his parents' gruesome murder.

In a December 16 press release, prosecutors described what they believe happened inside the couple’s Brentwood home.

"In approximately the early morning hours of December 14, Reiner is accused of fatally stabbing Rob Reiner, 78, and Michele Singer Reiner, 70, at their home in the 200 block of South Chadbourne Avenue in Brentwood,” Los Angeles County District Attorney Nathan J. Hochman stated. "Nick Reiner fled but was arrested hours later that evening in Exposition Park."