Diagnosed with brain cancer, his left eyebrow stitched from recent surgery, U.S. Senator John McCain appealed to civilities all but forgotten this week when he advised colleagues, “Let’s trust each other. Let’s return to regular order.”

McCain was speaking about the Senate’s tortured efforts to repeal and replace the Affordable Care Act. But he could have been talking about California.

Despite its self-image as an enlightened castle of political maturity standing apart from a nation filled with debasement and insult, California has begun to succumb.

Recent weeks have seen California politics deteriorate into behavior more familiar with the playground, gutter and Washington.

For evidence, let’s begin with State Assembly Speaker Anthony Rendon of Paramount, who with his family received death threats when he decided to sidetrack legislation that would create universal healthcare in California.

While California proudly views itself above and beyond the bottom-fed politics that thrill and incite audiences in fly-over states, the mobs have breeched the Sierra Nevada and stormed our beaches.

“The threats that I’ve received are threats that, unfortunately, seem to be sort of a standard part of American politics these days,” Rendon said.

He’s right. Rendon, whose leadership has been noteworthy for its probity and bipartisan outreach, didn’t forever silence consideration of the universal health care legislation, named Senate Bill 562.

He simply said that without a stable funding source, there was no point in considering the proposal this year.

Rendon knows California legislative sessions run on two-year cycles. January brings renewed opportunity. If universal health care advocates can be encouraged to spend the next five months identifying reasonable methods to pay for their grand ideas, they would find a friend if not an eager accomplice in the Speaker’s corner office.

But that’s not what modern political advocates do these days, not even in enlightened and progressive California. Rather than address Rendon’s faithfully expressed and legitimate concerns, the universal health care coalition transformed their position into a theatrical experience.

A mob formed and held demonstrations at the the capitol. They chanted oaths against Speaker Rendon. They presented dramatic entertainments, complete with a fake knife plunged into a protester costumed as a bear. They invented a nursery rhyme, “Rendon, Rendon shame on you. Action now on 562.”

And they made death threats to Rendon and his family.

What the universal health care believers failed to do was give Rendon any reason to reconsider his decision or build support for SB 562 next year. That would have required serious work and brainpower, infused with a recognition of fiscal responsibility and budgetary realism. And that would have erased the mob from the evening news.

The anti-Rendon dramatics were largely a Democratic Party affair, with pitchforks supplied by an allegedly progressive union, the California Nurses Association, which sponsored SB 562. But of course the state’s Republican minority has not been able to escape the spiral into mob behavior.

Assembly GOP leader Chad Mayes of Yucca Valley narrowly survived being removed as minority caucus leader after he supported Gov. Jerry Brown and voted to extend the state’s cap-and-trade climate change strategy.

Significantly, the environmental package featured elements to win GOP support: an extended tax credit for manufacturers and repeal of a fire prevention fee that Republicans claimed was an illegal tax.

The sweeteners convinced Mayes and six other Republican Assembly members to support the governor’s plan. They gave the bills a two-thirds majority.

Infuriated by the bipartisan GOP support, executive board members of the Republican National Committee organized an effort to remove Mayes as minority leader.

Mayes out-maneuvered the RNC board members and called a quick caucus vote to reaffirm his position. But his salvation may be only temporary.

So far, the Mayes matter is all standard insider political stuff and barely worth noting. But the story doesn’t end here. Hours before the vote, a murky, pro-Donald Trump website leaked highly personal and embarrassing information about Mayes and his family.

Mayes and his wife are in divorce proceedings. The website material, picked up and published and broadcast by media across the state, was presented to humiliate the Assemblymember and confirm salacious rumors that have circulated around Sacramento for many months.

Needless to say, the embarrassing material had no connection to cap-and-trade, climate change, Gov. Brown, taxes or the environment. And it’s difficult to imagine a right-wing fringe website would post negative information about Mayes if the GOP leader had refused to support a Democratic governor.

In the mob’s mind, the real sin committed by Mayes didn’t involve his marriage vows, but rather his bipartisan decision on climate change. He could not be persuaded to reverse his position by legitimate arguments of fact, logic or philosophy. He broke the party line.

So he and his family had to be publicly humiliated.

The hollowing out of our democratic institutions, from Washington to Sacramento, will continue until we listen to McCain’s plea for trust and order.