If you want to really get to know Donald Trump’s fervent rally supporters, you’d better get there early. And I did just that.

I got there in September 1968. As a young correspondent for Newsday, I first discovered the unpredictable potential of presidential campaign rally-goers who were mad-as-hell and not-going-to-take-it-anymore when I was covering the independent candidacy of segregationist/populist Gov. George Wallace of Alabama. When he took his independent campaign for president out of Dixie and into the north’s Rust Belt, he drew large crowds. And contrary to conventional wisdom, my interviews showed Wallace’s northern appeal had little to do with racism. Dozens of blue-collar Democrats shocked me by saying they had favored liberal Sen. Robert Kennedy until he was assassinated in June; but now liked Wallace. Why? Because, they told me, Kennedy and Wallace were the only two politicians who seemed to be “talking to people like me.”

The next time I encountered similar populist clout was in July 2015, at Donald Trump’s rallies. He’d been running for president for just one month. But folks who knew little about his stand on issues just knew he was the only one talking to folks like them! TV comedians and journalists were dismissing Trump as just a national punchline when I wrote on July 21, 2015, that people shouldn’t be shocked a year later if, on Election Night 2016, they discover “America’s fed-up, mad-as-hell voters just chose your next president.”

Today, looking ahead at 2020, I need to factor in the new realities that have been created by Trump’s populist zeal — and the folks who dig it. But now we also need to focus not just on our leaders’ failings, but our own.

More than ever, voters seem to want to get their news from whatever media will tell them what they want to hear — whether true or not. And they want to get their promises from pols who will tell them whatever they want to hear — whether it can be delivered or not.

Enter President Trump. He has rewritten all conventional wisdom, which was based on notions that a politician can be destroyed by news showing he deliberately lied. Trump has told thousands of lies. But many folks don’t much care if fact-checkers prove they are being lied to — as long as the lie makes them feel good.

It gets worse. Trump has proven that many people are now so fed up that he can manipulate them into hating his (and their) political enemies — and loving the politics of hate.

And that was the saddest reality we witnessed Tuesday night, when he formally kicked off his re-election campaign in Orlando. Trump skillfully and even gleefully mastered the art of manipulating his supporters into becoming his instruments of hate — and did it throughout his 76-minute speech.

In the first minute of his speech, Trump deliberately ignited the first of many hate-based audience chants. Gesturing at his impressively filled arena, he said: “Y’know, if we have about three or four empty seats, the Fake News will say, headlines: ‘He didn’t fill up the arena!’” Trump paused; his crowd, sensing its cue, booed lustily.

Three minutes later, Trump spoke of his impressive economic statistics, but ruined his good news by pointing at TV cameras and slowly sneering: “Ask — them — right — there!” He paused so his claque could chant: “CNN SUCKS!” Then Trump added: “That is a lot of Fake News back there!” He walked away so the chant could grow for two minutes. Next he mentioned Hillary Clinton, just so his chanters could revive their greatest hit: “Lock her up!” Next came another attack on journalists.

Finally, Trump launched his hate-bait finale: He told his now-frenzied crowd every time he is attacked: “They are really going after you!”

Trump’s tirades fuel his base, but also drive away others who cannot countenance his misconduct.

Sadly, there is one final cost we cannot ignore: We have seen tragedy that can result when a zealot with a gun gets spun by rages of hate. When a left-winger with a rapid-firing gun attacked congressional Republicans on a baseball field, we all grieved; thankfully Rep. Steve Scalise, R-La., and others recovered from their wounds.

But we all know, deep down, that our president’s politics of hate will probably plunge us into another national tragedy, sooner or later. Trump’s manipulative vehemence will someday push some unstable backer into a horrendous act. And yes, his next incendiary act could place one of my news colleagues into the crosshairs of tragedy.

Republicans who have been there may be our best and only chance. Hopefully, one or more of them will summon the humanity and faith-based fortitude to convince our leader to cease fire, now. Before it is too late.

Martin Schram is a columnist for Tribune News Service.