Is Donald Trump more than just a political fad?

Suddenly, we’re all living in Donald Trump’s one-man reality show.

He has hogged the airwaves and reduced the other Republican presidential candidates to supporting cast members who respond to the agenda he sets and react, at the insistence of panting reporters, to the constant barrage of his verbal grenades.

He has also thrust the matter of immigration to the fore of the 2016 campaign, to the great discomfort of those in his party who hoped the divisive issue would have been settled by now, or at the least been shoved to a far corner of debate.

What is less clear is whether Trump’s disruptive candidacy will have any lasting impact, assuming — as many analysts and political professionals do — he fails to win the GOP nomination, much less the White House.

Skepticism abounds, in great part because his success is grounded so thoroughly in Trump’s personality — large, loud and determinedly uncouth — and his status as a Washington outsider, as opposed to any broad philosophy or set of governing principles.

“Trumpism isn’t anything without Trump,” said UC Irvine’s David S. Meyer, who wrote “The Politics of Protest,” which charts the history of social change from the Boston Tea Party to the civil rights movement.

Personal charisma or, absent that, an ability to draw widespread attention, is crucial to any insurgent candidate and, Trump, a blissfully ostentatious billionaire and former reality TV star, has proved an unparalleled master of self-promotion. “But,” as Meyer pointed out, “it only takes you so far.”

TRAIL GUIDE: All the latest news on the 2016 presidential campaign >>

For all his headline-inciting flamboyance, Trump is hardly unique. The New York real estate magnate is just the latest in a long line of political upstarts and Washington outsiders — left, right, center — who have tilted at the nation’s capital and its governing class, tapping a hostility that, from the country’s founding, has simmered barely below the surface.

Some shattered racial or gender barriers. Many challenged the status quo. However, reaching back as far as the 1930s, only a handful of unsuccessful presidential hopefuls left a meaningful legacy once their campaigns ended.

Louisiana Democrat Huey Long never actually ran for president: He was assassinated before he had the chance. But he developed a national following during the Great Depression by promoting a populist “Share the Wealth” platform that targeted income inequality and promised relief for the masses of suffering Americans.

The mere prospect of a Long challenge helped prod President Franklin D. Roosevelt to enact a second round of New Deal programs, including Social Security, which emulated his rival’s proposal for a government old-age pension.

Decades later, Arizona Sen. Barry Goldwater was routed in a presidential landslide of historic proportion. But his 1964 campaign laid the groundwork for a conservative takeover of the GOP, a conquest that led 16 years later to Ronald Reagan winning the White House.

Four years after Goldwater’s unsuccessful campaign, Alabama Gov. George Wallace waged an angry, fulminating bid for president. Running as an independent, he won a handful of Southern states. More significantly, his race-based appeal to rural whites in the South and disaffected blue-collar workers in the North helped pry those voters loose from the Democratic Party and deliver them to the GOP, a realignment that persists to this day.

The common thread suggests it is ideas, not the individual pushing them, that ultimately prevail.

NEWSLETTER: Get the day’s top headlines from Times Editor Davan Maharaj >>

Perhaps the best analog to Trump is billionaire Ross Perot, who offered himself in 1992 as a blunt-spoken, problem-solving alternative to the two major party candidates and the same-old Washington same-old. Amid a national wave of Perot-mania, as it was then called, the entrepreneur led general-election polls for a time, until his paranoia and erratic campaigning undermined his third-party effort.

Still, he managed to turn his pet issue, the federal budget deficit, from a dry abstraction into a topic of countrywide concern. In the last week of the race, a Pew Research poll found that 40% of voters said reducing the federal deficit was the most important thing for the next president to accomplish, more than reducing unemployment — even as the country crawled back from recession — or managing healthcare costs, which Democrat Bill Clinton made a centerpiece of his campaign.

Long after Perot returned to private life, his obsession continued to shape the country’s fiscal policy.

Trump, by contrast, has largely avoided specifics, beyond a promise to do things bigger, better and bolder than anyone who has ever come before. There is no coherent ideology, no simmering issue he elevated to national discussion.

While he has churned up the immigration debate, the issue has been fought over — fiercely at times — for more than two decades. Even today it animates just a portion of the GOP and its conservative base.

In the moment, Trump has proved an irresistible force. He sits atop Republican opinion polls, though sentiments at this stage of a presidential campaign are notoriously fleeting. His backing, generally in the 20% to 25% range, is enough to lead an exceedingly large field but not overwhelmingly; polls also show Trump atop the list of contenders who voters say they would never support.

In the short term, Trump’s many intemperate remarks will live on, even if he fails to survive the primary season. Democrats, counting on the strong support of women and Latino voters, will make sure of it.

But beyond that, to be of very much consequence, Trump will have to do more than draw big crowds, or cause jaws to drop at his latest flurry of insults.

He’ll need to show his campaign is about something larger than himself.

Follow @markzbarabak on Twitter for national and California politics.

MORE POLITICAL COVERAGE:

John Kasich might have a little Donald Trump in him, and he’s a threat to Jeb Bush

Fiorina, once an afterthought in GOP race, fends off attacks and fights for a debate slot

Scott Walker sides with Trump on immigration and offers alternative to Obamacare