The first evidence that something was amiss in the American electorate came last February 20, when Donald Trump won the South Carolina primary. You don't need to be steeped in the minutiae of United States politics to work out why that happened - all you have to do is clear out all Trump's talk about walls and borders and focus on the US' intervention in Iraq.
That's right: Iraq.
During a televised debate before the South Carolina primary, Trump attacked fellow Republican Jeb Bush by focusing on George W Bush, his brother and former president. George, Trump said, had "lied" about why the US invaded Iraq.
"They said there were weapons of mass destruction and they knew there were none," he said. Trump's claim brought howls from political experts who confidently predicted that the claim would cost Trump votes. South Carolina, they said, loved the Bushes.
But when the votes were counted, Trump had won. Numerous accounts told the tale: Trump beat Jeb by "campaigning against nearly everything" that his brother George and his neo-conservative pals stood for, including the US' catastrophic Iraq intervention and the resulting conflagrations from Syria to Libya that it spawned.
Commonalities of anti-establishment
Now, three months later, the New York mogul is the presumptive nominee of the Republican Party. And while it's easy to dismiss his triumph by claiming that the public has been seduced by a media savvy "liar", "birther" and "bully", the truth is more complicated.
South Carolina showed that while Americans question Trump's character, when it comes to military adventurism, they're with him.
Oddly, the only other candidate who has stood with Trump on the Iraq War is Bernie Sanders, who has attacked Hillary Clinton for supporting Bush's intervention.
The insurgent current in the American electorate is undeniable. The old orthodoxies are melting away.
But opposition to the Iraq intervention is not the only thing Trump and Sanders agree on: Both have questioned the effect of the US' free trade principles, blasted the North American Free Trade Agreement and rejected Barack Obama's Trans-Pacific Partnership trade deal.
More crucially, Trump agrees with Sanders about the 2008 financial meltdown, which Sanders blames on the Republicans. "When the economy crashed so horribly under George Bush because of the mistakes they made with banking and lots of other things, I don't think the Democrats would have done that," Trump said in July 2015. It was a remarkable Sanders-like statement.
The foreign policy and financial "elites" have noticed these similarities. Trump's victory has scared the hell out of establishment Republicans, who are migrating to Clinton's campaign, while Republican neo-Conservatives see in Clinton a symbol of their unapologetic militarism.
The most prominent among them has been Max Boot, a self-described "American imperialist" who has never seen a war he wouldn't send someone else to fight. "For all her shortcomings ..." he recently wrote, "Clinton would be far preferable to Trump."
The Democrats' Max Boot is economist Paul Krugman, a liberal free trader who says Sanders has adopted "easy slogans over hard thinking". Krugman's resume is not in question, but he's never had to live paycheck-to-paycheck like large numbers of Americans.
While it is unlikely that Sanders will beat Clinton for the Democratic nomination, that hasn't stopped Krugman from calling Sanders' supporters "idealists", "romantics" and "purists".
Neophytes vs elites
Boot and Krugman have this in common: they love experts. Boot recently complained that Obama's chief foreign policy adviser lacks an advanced degree in "international relations, defence, area studies, or any related field", while Krugman tells us that every "serious progressive policy expert on either healthcare of financial reform" supports Clinton.
The message is the same: instead of listening to neophytes such as Trump or Sanders, American voters should put their trust in the experts - that is, the same people who gave us Iraq and bankruptcy.
Which is not to say that Sanders is a Democratic Trump. He's not: He calls Trump's immigration policies "crap", describes Trump's views on women as "disgusting", and slams Trump's anti-Muslim screeds as "an embarrassment to our country".
Nor is it to claim that Sanders voters will make Trump their second choice. They won't: Only 15 percent of Sanders voters say they'll vote for Trump if Clinton gets the Democratic nomination.
Even so, the insurgent current in the American electorate is undeniable. The old orthodoxies are melting away.
Indeed, the odd confluence of the Trump-Sanders critique of the US' military misadventures and Wall Street's financial misdeeds have shown that, while elections are almost always about the future, this one is about the past - it's about holding those responsible for the thousands of dead in Iraq and the bankruptcy of the country accountable for what they have done.
Mark Perry is a Washington DC-based foreign policy analyst and author of Talking to Terrorists: Why America Must Engage with its Enemies.
The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.