President Biden's supporters can be a temperamental bunch, just like the man they support.

Even with the departure of more prominent supporters, Hollywood High Roller While George Clooney and Rob Reiner have said it's time for Biden to step aside and former House Speaker Nancy Pelosi has said she doesn't want Biden to continue in the race, true Biden supporters are holding back.

Of course, some people, like California Governor Gavin Newsom and some representatives and senators, think Biden should stay the course, but I've heard direct outrage from readers over my column suggesting that Biden undergo a series of neurological tests (based on evaluations by doctors I spoke to) to reassure the public that he's OK, as he adamantly maintains.

“He should get tested and make the results public,” said Dan Cordova of Albuquerque. “He should retire and hide.”

“Shame on you for joining the Biden coverage frenzy,” wrote Marcy Rosenberg of Porter Ranch. “It's already been reported that President Biden has arthritis. Stiff back makes him walk slowly. He can still ride a bike. What about Donald? No, he can't even walk on a golf course.”

Even former state Assembly member and Los Angeles County Supervisor Sheila Kuehl has brandished a stick at me.

“Instead of joining the ignorant drumbeat of echo journalism, perhaps you could [history professor and essayist] Heather Cox Richardson A letter from the president's personal physician was made public. [Kevin] Ms. O'Connor will undergo a neurological examination at the end of February. I hope that you will read her story and shed light on this in your column, just as thousands of you do every day.”

I understand and respect Biden's loyalty, and as I've said before, he's a decent, respectful person and a good president.

I too believe former President Trump is a threat and have said this many times, but I don't know who the bigger threat to the Republic is – Trump or all the lemmings who are trying to give a second term to a lying, hateful, vengeful, self-centered felon who failed to deliver on most of his campaign promises (look it up if you don't believe me).

A reader asked me why I wrote that Biden should be tested but not Trump, who has unique behavioral issues. I thought it was obvious that Trump should be examined in the head. But of course I'm in favor of both of them getting a full diagnostic test.

I loved the suggestion from Terry Spencer of Highland Park that Biden and Trump should both take an intentionally confusing California DMV license renewal test and whoever gets the highest score should win the election.

Biden supporters seem to fall into one or more of three categories: those who believe Biden's health is good enough to continue to serve, those who think it's too late to switch to an alternative candidate, and those who would vote for a bean-and-cheese burrito before voting for Trump.

“I don't put much faith in the polls, but Biden still has a better chance against Trump than any other candidate,” Kuehl said, adding that the confusion of “switching horses midway” would “do more damage to the party than supporting Joe. I think Joe will win.”

That seems plausible, but the river is deep and the horse's head is barely above water.

One reader, Mark Richardson of Encinitas, is hoping the baton will be passed, but it's not time yet.

“We'll see what happens in the next few months. If he is elected, he can step down in January 2025, one month after Inauguration Day. [Vice President Kamala] Harris can take over,” Richardson said.

This is also plausible, but the key words are “if he's elected.” I have serious doubts, and said earlier this month that Biden should pass the baton and step down with pride, dignity and grace — not because of age (many of the older generation are fully functional), but because of health.

The president's awkward gait, sloppy facial expressions and stumbling speech during the June 27 debate did nothing to improve his chances of victory. Nor did his judgment seem sharp. Instead of being drawn into a pointless argument about which candidate is the best golfer, Biden should have said that with the Earth melting and women's reproductive rights being taken away by Trump's Supreme Court, he would rather talk about saving the country than play golf.

The ABC interview, which aired a few days later, didn't make things much better for Biden, and many questions remain about the doctor's report cited by Kuhl and countless others, based on Biden's February medical exam.

“A very detailed neurological examination again gave us reassurance that there were no findings consistent with cerebellar or other central nervous disease such as stroke, multiple sclerosis, Parkinson's disease or ascending lateral sclerosis, and no signs of cervical myelopathy.” The report states: From Biden's doctor.

No matter who is president, I do not take any statements from the White House as absolute truth and I question them.

When exactly was the neurological exam performed and by whom? What does “extremely detailed” mean? Given the progressive nature of his memory and movement problems, is it possible that Biden's condition has changed over the past six months and will continue to change?

As Kuhl points out, there is a big difference between the opinion of a doctor who makes a diagnosis from afar and the opinion of a doctor who actually examines the patient. I couldn't agree more, and in fact wrote a column criticizing people who think they can diagnose dementia by watching Biden on CNN. Dementia is not a catch-all term for memory loss caused by a variety of factors.

But no matter how much you love Biden, hate Trump, or both, it's hard to imagine anyone watching that debate not worrying about Biden's health.

Neurological movement disorders often have specific symptoms that doctors can spot. Several people contacted me after the debate to say they saw signs of Parkinson's disease or a related condition. Two neurologists noted Biden's blink rate, facial expressions, stiffness and speech pattern.

One of them, Dr. Michael Mahler, a neurology expert and faculty member at UCLA, said he has some doubts about the “Parkinson's disease” paradigm.

Dr. Jack Florin, a professor at the University of Southern California and former research associate at Stanford and Harvard, said he believes Biden may have a variant of Parkinson's disease called progressive supranuclear palsy (PSP), which can involve cognitive impairment that worsens over time and can affect mental processing speed, attention and concentration.

The White House report on Biden's health did not convince Mahler and Florin that we know the full story or that their impressions of Biden's condition were off the mark. Florin suggested that an MRI, if one has not already been done, would help support his theory that Biden has PSP.

Mahler said some of the impairments in the Parkinson's field are variable in nature, meaning they change over time, and that a “normal neurological exam in February (or earlier) means nothing to someone who has a stroke or a series of mini-strokes in March.” But he was cautious about making a specific diagnosis, saying medications for certain disorders can cause symptoms that resemble Parkinson's.

“One of the things Biden has said repeatedly is that the role of president is a tougher test than asking someone to draw a clock or remember five words, and that's probably true,” Mahler said. “But it's also true that neurologists across the country saw something during the debate that was nothing short of reassuring: that the president is in neurological health.”

What I witnessed was a sad moment in American political history.

A tyrant hoping for victory in November.

A weakened president is standing tall.

Some of his supporters have abandoned him, while others have become even more supportive.

Neither candidate may be tested, but we will all be tested in November.

Email: steve.lopez@latimes.com