There are lots of theories about Donald Trump’s appeal. Is it his celebrity in this Age of Kardashians and his ability to self-fund? Or is it something even more basic. Perhaps he picked the perfect year to finally run after toying with it since 1999, five presidential cycles ago.

Voters are in the midst of an extended period of pessimism with more than 60 percent saying the country is on the wrong track.

The lower the trust in government the better it is for outsiders—think Jimmy Carter post-Watergate in 1976 and Barack Obama post-Bush and Iraq in 2008.

“The bottom line is that you turn to outsiders when you lose faith in the insiders, and the GOP elite is unable to address a lot of issues people care about,” says Sam Popkin, a political science professor at the University of California San Diego.

Trump filled the void by brazenly talking about the issue that apparently matters most to Republican primary voters, which is immigration. “It’s why so many people want to hear him,” says Popkin. “They say they like him because he’s not politically correct. He says what’s going on. Like George Wallace, he knows how to get right to how people say it in the bars while all the elites tiptoe around trying to behave.”

The Republican establishment, what’s left of it, is extremely uneasy about Trump and how he’s changed their party whether he wins the nomination or not. “You don’t have to win the nomination to win the conversation,” says Popkin. The other candidates have been reluctant to call him out either because they don’t want to risk his wrath, or they don’t want to offend his voters. Either way, “When racism and xenophobia is there, and you pretend it’s not there, you’re helping Donald Trump.”

Popkin is the author of the groundbreaking book The Reasoning Voter, published in 1994, which argues that “low information voters” absorb enough in everyday life about candidates and their character and their likely performance as president to make a rational choice in the voting booth.

“We’ve had these characters over and over,” says Popkin, citing George Wallace, though he was more directly racist, and Ross Perot, who never talked about God and the Bible, yet held the religious base of the party with the budget deficit.

“In country after country there’s a Trump these days because every country has nativist, anti-immigration sentiment growing.” The difference is that it is easier to get further in America because of the primary system. In other countries, candidates like Trump form fringe parties. If Trump wins Iowa and New Hampshire and South Carolina, he would be hard to stop.

Before wringing your hands and saying nothing like this has ever happened before, Popkin brings up the ’60s. “The Republicans are behaving the way the Democrats did in the ’60s. Young people wanted to talk about race and gender, and old people wanted to talk about union wages. Young people wanted to talk about feminism and police brutality, and forget about the unions.” Economic issues got lost, and cultural issues held sway. Oh, and the Democrats lost.

Trump supporters don’t see him as a loser. They buy into his campaign rhetoric; they believe he can do anything. “They’ve seen him so many times and he seems so competent when managing all these economic crises,” says Popkin, who remembers that for six years in the 1980s the Central Park ice-skating rink was mired in bureaucracy, “and he got it done in six months. He became a hero over that. He’s a well-known moneymaker that people have seen firing people on TV a million times. It looks awfully real to people. They’re saying exactly what they said about Ross Perot: He can’t be doing it for the money because he’s so rich. It must be public service.”

The more mainstream GOP candidates struggle to explain any lapse from GOP conservative orthodoxy while Trump effortlessly co-opts the anti-immigration, nativist element in the party. “He’s redefining conservative as someone who hates Mexicans and Muslims. He’s taken the easy piece in the coalition. Forget about the religious people and the billionaires—I’ll take care of you guys who have Mexicans messing up your communities.”

While “horrified” by much of what Trump says, Popkin can’t help but admire the sophistication of the way he demolishes other candidates, and has remade the GOP in his image. “It’s his party now. He’s not filtering it and that may make it impossible to get beyond 30 percent of the electorate, but it’s enough to get power within the party. He matters whether or not he gets the nomination.”

Trump has tapped into a sense of grievance about a lost America in an increasingly multicultural country. “He is out in the open about the discomfort of having so many Spanish-speaking people in the country,” says Popkin. And whatever happens to Trump in the nominating process, he’s hurt the GOP’s already diminished brand when it comes to minority voters. “There’s no way to kiss and make up with Hispanics, to say, ‘We’re sorry we didn’t stop this sooner.’”

That sounds like an epitaph for the Republican Party on the presidential level, but Popkin doesn’t go that far. “With fear of ISIS and terrorism, it’s never over. Who knows how bad the fear? Who knows what they will do next? It would take enormous events for Trump to win, but he’s done enough already to change the game.” As for the reasoning voter, their determination is based on what’s best for them, not on any collective good, however loosely defined. And for that narrow set of interests, there is no better pitchman than Trump.