Donald Trump’s success represents a rare phenomenon in which the perfect messenger perfectly captures a pervasive mood. And while those who grow increasingly horrified by the messenger and his demagoguery search for a scapegoat to blame, the fact is the mood Trump has tapped into so deeply has been festering quietly for decades.

Through the middle of March, Trump has won 15 of the 28 Republican presidential nominating contests to date. Exit polls show his supporters cross many demographic lines: He wins among Christian evangelical voters, and among those who call themselves moderates; he does well with men, with women, with younger voters and old folks.

But within those numbers, a pattern becomes clear: Trump does best among voters who have seen their personal relationship with the U.S. economy change most dramatically over the last several decades. Trump does best among voters who have not attended college, and those who make less than $50,000 a year.

For these voters, the unemployment rate remains higher than the national average, the labor force participation rate well below the national average. The blue-collar manufacturing jobs once available in textile plants in South Carolina, or auto factories in Michigan, or mills in Kentucky or Massachusetts or Virginia — all states Trump won — have shuttered or cut workforces in the decades since NAFTA.

The economy has changed for these Americans; Trump has promised a return to the greatness they once knew, a greatness robbed by the spectral other, those who have supposedly taken their jobs away, south to Mexico or east to China.

That Trump’s supporters are almost entirely white is a function that goes beyond the fact that few non-whites vote in Republican primaries. Polls show huge majorities of African Americans and Hispanics see Trump unfavorably, despite his protestations to the contrary. Trump’s appeal to economically down-scale whites rests on the founding premise of his campaign, that the America they once knew is gone, and that only a strong leader can bring it back.

Those voters are far more likely than the rest of the populace to believe Trump when he tells them things are going wrong; 75 percent of whites say the country is headed in the wrong direction, and just 42 percent believe their financial situation is likely to get better over the next six months. Both African Americans and Hispanics face higher unemployment rates than these white voters, but they are far more optimistic, both that the country is headed in the right direction and that their personal situation will improve.

It has been a rough few decades for these blue-collar white workers. They are more likely to have suffered factory closures after NAFTA, their children are more likely to have signed up to fight the wars in Iraq and Afghanistan, and the economic recovery that has been so good for those who own a piece of the stock market has failed to raise their hourly wages. Tax cuts passed during the Bush administration did not help their pocketbooks; the Affordable Care Act may not have directly benefited them. Leaders in both parties, many of these voters believe, have left them behind.

That message has been enforced, repeatedly, by the very politicians now lamenting Trump’s rise, sometimes openly and sometimes subtly. The notion that President Obama is a foreigner who means harm to the nation has been quietly reinforced, whether through viral emails, by ideological news outlets hungry for internet traffic or by politicians willing to use false rumors and the perceptions they leave to their own advantage.

Exit polls in states that have already voted include one more telling figure: Consistently, Trump wins 75 or 80 or 85 percent of the vote among those voters who say they want a candidate who “tells it like it is.” To these voters, something is going unsaid, and Trump — the candidate who has not only derided Hispanics, women, veterans such as Sen. John McCain, the disabled and a litany of others but also redoubled those insults by refusing to apologize — is the one who is saying it.

Trump’s lack of a coherent ideology, and his departures from modern Republican orthodoxy, matter far less than his perceived willingness to remain unfettered, to remain politically incorrect. He represents a kind of permission to give voice to the dark thoughts that have bubbled in the minds of those who fear they are being left behind, to the benefit of those of other races.

It is not hard to imagine why Trump’s appeal has resonated so much with his voters. After years of increasingly heated rhetoric from both sides — the left questioning the legitimacy of George W. Bush’s victory in 2000 and the right questioning the legitimacy of Obama’s right to hold office in the first place — Trump has captured the imagination of so many by simply using more extreme rhetoric.

He has demonstrated little use for nuance at a time when voters believe their personal economies, their livelihoods, the country they know and love is at risk.

Throughout the two centuries of American history, other moments like this have existed, when a particular gregarious personality captures the national imagination. Some, like Ronald Reagan and John F. Kennedy, have tapped into the nation’s naturally deep well of optimism; others, like George Wallace and Joseph McCarthy, have played to darker inclinations.

The fad of Trump, like all others, will eventually pass. But the raw emotion of his disenfranchised, disconnected and deeply distraught supporters fueling his campaign now has been building for decades. As the pace of demographic and economic change in America picks up, those voters will occupy a smaller piece of the political pie. But there is no reason to believe their anger won’t continue to grow.

This article was originally published on Morning Consult.