Ignore middle-class, working-class voters at your peril.
That's the lesson Republicans have learned as the Summer of Trump became the Year of Trump, with the real estate mogul's April 26 sweep all but sealing the nomination regardless of how much rival Sen. Ted Cruz and the Republican establishment kick, scream and cry foul.
"I've just never seen us so thoroughly screwed up," a Republican strategist told the New York Times. "Maybe we really do need time in the wilderness to figure out what we don't get about our own voters."
Indeed. Get out of Washington, surround yourself with people who aren't congressmen and senators who have been serving since the 1970s. Observe life in regular American small towns and cities when they're not overrun with politicians trying to shake a thousand hands on a primary day. See what life's like for regular people, who don't have six-figure jobs with lobbying firms waiting for them if things don't pan out.
Most importantly, put yourself in their shoes.
Try to understand what it's like living paycheck-to-paycheck while a group of millionaire and billionaire politicians -- who are supposed to represent your interests -- rub elbows with corporate CEOs and investment bankers at $1,500-a-plate fundraisers.
Watch the middle class shrink before your eyes as your tax policies and your favorable-to-the-rich legislation relegate them to the lower class, like European football teams that can't compete with the Real Madrids and Barcelonas.
As the Times points out, Democrats shouldn't be gloating either, not when their establishment candidate is getting ambushed at rallies by furious members of her own party, taking her to task for her own tone-deaf policies and cozy relationship with Wall Street.
The Democrats have lessons to learn too, and they'd be smart to study the Trump playbook -- and the attitudes of avowed Trump supporters -- before attacking him in a general election contest.
It's easy for Democratic strategists to dismiss Trump voters as bigots and xenophobes, but insulting a large cross-section of the American public doesn't exactly inspire them to vote for your candidate, especially when not-insignificant numbers of your own party are still wallowing in the aftermath of a recession.
Democrats, the Times points out, were blindsided by the anger in their own electorate, the frustration that fueled the campaign of Vermont Sen. Bernie Sanders and turned the primaries into another long slog for Hillary Clinton.
Dismissing Trump's voters, waving them off as insignificant, or underestimating the candidate himself is the kind of hubris that got Republican elites in trouble in the first place, former Republican congressman -- and current MSNBC political host -- Joe Scarborough wrote in the Washington Post.
"So why did these 'narrow elites' miss the mark so badly when the topic turned to Trump?" Scarborough asked. "Because most of them are hopelessly isolated from the other 300 million or so Americans who inconveniently share their country."
The April 26 primary results point to a Clinton-Trump general election, barring any indictments, catastrophes or miraculous comebacks. Like a new playoff round, the scoreboard is reset, the chess pieces moved back to their original positions.
For Democrats, the game against Sanders was a warm-up. An important warm-up, it turns out, since Sanders' populism could be termed Trump-Lite, or at least Trumpesque with a lot more tact. Trump isn't a typical candidate, and the typical political playbook won't be enough to defeat him.
If the DNC doesn't want to end up like the GOP, its leaders should make sure the party quickly learns the lessons it took Republicans the better part of a year to learn.