DES MOINES — He's proposed a wall at the Mexican border. He's described immigrants as criminals, rapists, and drug runners. He's questioned the heroism of a Vietnam prisoner-of-war who eight years ago won the Republican presidential nomination he now seeks. He's displayed an unsettling preoccupation with the bodily fluids of women.
And he's prompted commentators and scholars from coast to coast and around the globe to say that America has never had a prominent political figure — never had a leading presidential candidate — never had a media magnet nor a business magnate — remotely like Donald John Trump.
Except perhaps we have. Trump — flamboyant and unfiltered — may not resemble any single figure in the American political tradition as much as he is a formidable combination of several of them: some from the left, some from the right, a mix reflecting Trump's own political provenance and profile.
There are echoes of some relatively recent presidential aspirants, from H. Ross Perot, the crusty, cocksure business mogul who, like Trump, promised in 1992 to use his executive smarts to fix what politicians had broken, to Patrick J. Buchanan, the fierce conservative who delighted, a la Trump, in lashing the viceroys of the political establishment and who terrified them by winning the 1996 New Hampshire primary.
But there are also longer historical threads to trace.
Conversations with a range of scholars, and some rummaging through historical sources, suggest that the most riveting figure in American politics today can perhaps be parsed as one part populist (recalling, in some ways, William Jennings Bryan, three-time presidential candidate and secretary of state); one part brilliant exploiter of public fears (Joseph McCarthy, senator and red-baiter); one part mesmerizing but inflammatory preacher (Father Charles Coughlin, supporter of Franklin Roosevelt and then bitter opponent of the New Deal), one part showboat (Jesse Ventura, gaudy professional wrestler, and governor of Minnesota), and one part crusading antielitist (Huey Long, governor of Louisiana, senator, and possible presidential candidate).
In some ways Trump — real-estate developer, television personality, presidential candidate with robust poll ratings — perhaps most evokes the aura, though not the shameless corruption, of the early Huey Long, described this way by the historian T. Harry Williams in his classic 1969 biography of the man known as the Kingfish.
''He excited people and he excited emotion, arousing in his relatively short but explosive career every feeling in the political spectrum — amazement and admiration, disbelief and disgust, love and hatred and, with many individuals, cold apprehension,'' Williams wrote.
But Trump is far more than Huey Long redux. His issues are contemporary: stagnant wages, fear of terrorism, contempt of government. He is an angry warrior against what he paints as the blindness of the bland in American politics.
And his persona is an amalgam — not, as some analysts have argued in recent weeks, of France's Marine Le Pen and the distempered voices of the populist Right of Europe, but instead of the anger of the back channels and tributaries of American history, all rolled into one campaign:
He is outraged — like Bryan. He is outrageous — like Ventura. He harnesses fears — like McCarthy. He is fearless — like Long. He takes advantage of economic unease but has an easy way — like Coughlin.
And his persona is especially appealing to anxious voters distrustful of politics and government, a man who projects absolutely no doubt about his ability to transform both.
"This campaign is about anxiety,'' says Sarah Purcell, a historian at Grinnell College, 50 miles east of Des Moines. "There's a huge loss of national self-confidence. We're in an economic recovery and it doesn't make any sense that there is so much uneasiness. A lot of Trump's rise can be attributed to fear that may or may not be real.''
But this much is real: Trump is a powerful force in American politics.
Two Americans out of five, according to a Wall Street Journal/NBC News Poll this month, consider Trump's statements insulting and the ''wrong approach,'' but Trump still remains at or near the top in polls here in Iowa, which on Feb. 1 holds the first caucuses of the 2016 political season, and nationwide. Indeed, the latest polls show Trump and Senator Ted Cruz of Texas roughly tied for the lead in Iowa.
Like so many of his predecessors, Trump feasts on a frustration that is a very real factor in a nation where, according to a Pew Research Center study, the American middle class is now smaller than the nation's upper and lower classes.
In this era of multiple public-opinion polls, where survey figures bounce around with frustrating regularity, there is remarkable agreement on one topic: Two-thirds of the American people believe the country is going in the wrong direction. And you don't have to be a professional pollster to understand intuitively that Americans' trust in government doesn't remotely approach the 77 percent figure recorded in 1964.
The result, as the first political contests of next year's presidential election approach, is huge crowds whenever Trump speaks.
"The thing about a Trump event is that these people know they're punishing decades of bad behavior by politicians,'' says Chuck Laudner, who is managing the Trump campaign here in Iowa. "They're voting for somebody, not against somebody. It's a huge difference, one that the national media won't recognize or acknowledge.''
Part of that 21st century appeal can be understood as the ideology of "so'': We're going to be so tough. So dominant. So nasty. So great. In an often-perplexing poltical season, it is an easy get — and, so far, an easy winner.
"His rhetoric is natural — but even his natural rhetoric is calculated,'' says Jennifer Mercieca, a Texas A&M University historian of American rhetoric. "If you've lost confidence in political leaders and our national institutions and in the financial industry and the news media, he's coming across as someone to believe in.''
And Trump matches his rhetoric with a personality well tuned to the moment — a man too rich to be bought by big interests, too self-assured to be swayed by the concerns of the party establishment, too blunt to be misunderstood.
In the early stirrings of the campaign, the Trump candidacy was on the periphery, a distraction, a colorful self-indulgence, with a political character much like the primary challenge Buchanan mounted against President George H. W. Bush in 1992.
"Voters do not want him to be president,'' the consultant Alex Castellanos, now a fierce Trump critic, said of Buchanan in a campaign memo to Bush. "He is the vehicle through which they can send George Bush a message.''
But the Trump campaign has evolved into something quite different, and something far more powerful. The sources of that power are manifold.
One is his willingness to express the thoughts widely held but sparingly expressed — in some ways like Joe McCarthy, who captured the real fears of many Americans in the 1950s before his anti-Communist crusade went off the rails and his power evaporated.
"McCarthy did not have a filter on him, and neither does Trump,'' says James L. Baughman, a University of Wisconsin historian. "He'll pretty much say anything, and his supporters think that's great. For him that's a strength rather than a symbol of his unfitness to be president.''
A second source of Trump's power is the appeal of his rhetoric, effective if not nearly as eloquent as that of Bryan, who first ran for president as the 1896 Democratic nominee and whose "Cross of Gold'' acceptance speech is one of the greatest addresses in American history.
The poet Vachel Lindsay wrote that "When Bryan speaks, the sky is wide/The people are a tossing tide,'' though a prominent German-language newspaper had a rather different take, decrying Bryan's "bombastic phrases in Western Methodist camp-meeting style.''
A third is his willingness, as in Trump's proposal to ban Muslim immigrants, to extend the range of political argument beyond ordinarily acceptable bounds.
In that he mirrors another, earlier media star, the aviator hero Charles Lindbergh, who enthralled Americans until his anti-interventionism veered into anti-Semitism.
His extremes prompted what his biographer, A. Scott Berg, called "a Niagara of invective,'' with Governor Thomas E. Dewey, the leading Republican of the time, describing Lindbergh's famous 1941 Des Moines speech tracing the growing push to intervene in World War II in part to Jewish influentials, as ''an inexcusable abuse of the right of freedom of speech'' and Wendell Willkie, the GOP's 1940 nominee, regarding it as "the most un-American talk made in my time by any person of national reputation.''
Still another is the strange but undeniable auditory appeal of Trump, which is the angry post-modern analogue of that of Father Coughlin, who was possessed of what Wallace Stegner called a voice so captivating "that anyone tuning past it [on the radio dial] almost automatically returned to hear it again.'' Coughlin was, as Stegner put it, a "parish priest addressing crowds such as no man had ever addressed before.''
A final element is Trump's surpassing self-confidence, which matches that of Long, whose sister once said that "Huey felt he was a man of destiny who was put here for a purpose.'' Trump holds a commanding lead among voters for whom being ''a strong leader'' is the most important characteristic for a GOP nominee.
No other figure in American politics today could distill his plan into four pugilistic sentences as Trump did in a radio advertisement broadcast before his proposal to bar the entry of Muslims: "I will stop illegal immigration. We'll build a wall on the Southern border. And yes, I will also quickly and decisively bomb the hell out of ISIS. We'll rebuild our military and make it so strong that no one, and I mean no one, will mess with us.''
Like Trump, Long was Velcro for attention. "He had to dominate every scene he was in and every person around him,'' Williams wrote of Long in a description that might be applied to Trump as well. "He craved attention and would go to almost any length to get it.''
Like Long, Trump uses the fecklessness of the political class to his advantage. This comment by Long is interchangeable, almost word for word, with Trump's trademark brand of repartee: "They think I'm so smart. Maybe I'm not. Maybe it's that there are a lot of dumb people in the world.''
And yet there are great differences between Trump and Long, whom Roosevelt regarded as the second-most dangerous man in America (General Douglas MacArthur was the first). Long emerged from the political swamp of Louisiana, what the crusading Southern newspaper publisher Hodding Carter characterized as a center "of genteel corruption, of steady political degeneration, of venality, of a studied neglect of civic advancement,'' while Trump emerged from a mature democracy with superpower status.
Long and Bryan almost certainly never met, but Long appropriated from a Bryan speech the phrase that would become his slogan: "Every Man a King But No One Wears a Crown.'' In eras a generation apart, the two pitched their appeal to workers and farmers, winning the opprobrium of the political elite of their eras, both marked by economic distress.
A quarter of GOP primary voters under age 50 without a college degree support Trump — but only half that many with a college degree do, according to a Wall Street Journal/NBC News survey.
"Trump is a creature of great fear — threats from without, threats from within,'' says Michael Kazin, a Georgetown University historian and a biographer of Bryan. ''The people who like him the most don't have the institutions they once had to defend them. They used to have unions. They used to have immigrant groups. He's their guy.''
There's an element of simplicity to the Trump appeal as well — one that has echoes of past political players, from the right and left.
"He reminds me a lot of Ross Perot,'' says former senator Rick Santorum of Pennsylvania, winner of the 2012 Iowa caucuses and a candidate again in 2016. "He'd say 'we're going to fix it,' and Trump is pretty much saying the same thing: 'I'll make it great.' It's the same kind of appeal that back in 1992 was attractive.''
As this campaign has progressed, some scholars — Trump opponents, mostly, skeptical if not contemptuous of his appeal — have placed Trump in the tradition of the "paranoid style in American politics'' that the historian Richard Hoftsadter identified a half century ago.
Hofstadter, who died 45 years ago, spoke of a sense of "heated exaggeration, suspiciousness, and conspiratorial fantasy'' as a powerful force in our political tradition.
But in a forthcoming book on recurring American culture wars, the Boston University scholar Stephen Prothero instead speaks of the importance of worry and apprehension in American political life.
A critical motivator in our politics, he argues, "is anxiety — anxiety about loss, about the passing away of a beloved 'way of life.' "
That — a surprising sense of nostalgia, from a candidate who has little impulse to sentimentality — may actually be at the heart of the appeal of Trump, as it was from the left for such figures as Bryan and Long, and from the right for such figures as McCarthy and Henry Ford, himself once considered a formidable presidential prospect.
Americans, says Trump campaign chief Laudner, believe old notions of government accountability and political responsibility have disappeared. "The federal government doesn't do anything right, and it's past embarrassing,'' he says. "It's both parties and it's a culture in Washington that refuses to serve the people who elected them.''
It sounds like a new siren call, but it's as old as the Republic. The contemporary presidential candidate whose rise is fascinating all America is, in his way, a fascinating all-American candidate.
David M. Shribman, a former Globe Washington bureau chief, is the executive editor of the Pittsburgh Post-Gazette. He can be reached at firstname.lastname@example.org .