From Barry Goldwater to Pete Wilson to Donald Trump: Is GOP on verge of losing Latinos for a generation?

Republican leaders are openly fearful that Donald Trump’s divisive presidential campaign will drive Latino voters away from the Republican Party for a generation or more, much in the way Barry Goldwater alienated African Americans during the civil rights era.

It was a similar lesson in California in the 1990s, when the state shifted from reliably Republican to bright blue in the aftermath of the heated 1994 anti-illegal immigration campaign led by then-Gov. Pete Wilson. Many believe that episode handed the Golden State over to Democrats.

Now Republicans worry that a similar shift is underway nationwide as Trump’s race-based campaigning repels even the most conservative Republicans, potentially marring the party as bigoted for years to come.

Among those most concerned is one who should know. Senate Majority Leader Mitch McConnell of Kentucky voted against Goldwater in 1964 because of the GOP nominee’s opposition to civil rights. He worries a half a century later that the story is repeating.

“My party has been struggling with African American voters ever since,” McConnell said recently. “I don’t want to see that mistake made with Latinos.”

The Latino community, he said, is “a big important part of America. For our party to be competitive, we have to be able to reach out to all kinds of people.”

Trump insists he is beloved by Latino voters. Earlier this week, he argued that those who were angry over his racially tinged comments about a federal judge overseeing a civil fraud lawsuit against Trump University should just “get over it.”

But Republican leaders know the problem is a very real one for the GOP, made up of both political optics and electoral math.

From the time Trump launched his campaign by calling Mexican immigrants “rapists” and vowing to build a wall along the Mexican border, his approach toward Latinos has upended Republican plans to portray the party as more inclusive and welcoming.

The rhetoric only intensified when Trump insisted that he would deport not just immigrants who are here illegally, but also their American-born children, as a way to keep families together.

More recently he sparked outrage by insisting he could not receive fair treatment from San Diego federal Judge Gonzalo Curiel, who is overseeing the lawsuit against his now-defunct real estate school, because the American-born judge’s parents were Mexican immigrants. Trump later tried to walk back those remarks, but still questioned the judge’s ability to be impartial.

“We don’t have to guess that they’re going to lose Latinos for a generation, because we saw it happen here in California,” said Matt Barreto, a UCLA political science professor and cofounder of the Latino Decisions polling firm. He is consulting for Hillary Clinton’s campaign.

Polling shows the California GOP’s embrace of Proposition 187 and an anti-illegal immigrant agenda in the ‘90s accelerated a decline already underway due to shifting demographics. The state has voted Democratic in every presidential election since.

Republicans believe Trump’s race-based statements – including an initial refusal to disavow former Ku Klux Klan leader David Duke and a reference to a black supporter at a rally as “my African American” – are similarly limiting the party’s ability to attract a wider swath of voters than its core base of white Americans at a time when the GOP had hoped to be reaching out to Latinos and minorities.

Latinos are the fastest growing part of an increasingly diverse electorate, according to the Pew Research Center. Nearly one in three eligible voters this fall will be Latino, Asian, African American or other minorities.

When Ronald Reagan was president in the 1980s, 85% of the electorate was white. By 2012, that number had dropped to about 74%, according to Pew.

“It’s a well-founded fear,” said Sen. Jeff Flake of Arizona, who has withheld his support for Trump.

To understand the depth of the party’s potential loss, scholars point to the dropoff in black Republican voters after the civil rights battles of the 1960s.

Republicans won 30% of black votes, on average, from 1948 to 1960. Since the 1964 election and Goldwater’s stance against the landmark civil rights bill that year, it has averaged less than 6%, according to an analysis by Claremont McKenna College professor John J. Pitney.

Trump’s unfavorable rating among Latinos nationwide is currently an eye-popping 87%, according to April polling by Latino Decisions, versus Clinton’s 22%.

Trump may be able to stem his losses among Latinos by turning out more white voters, who fueled a record-setting GOP primary voter turnout. But Republicans see little consolation for what has become a potentially irreversible slide.

Republicans have been losing Latino voters in every presidential election since President George W. Bush hit a high point in 2000 by winning more than 40% of the Latino vote.

Latino support dropped to 27% for Mitt Romney in 2012, stung partly by his suggestion that illegal immigration could be resolved with “self deportation.”

“I wouldn’t put it entirely on Trump,” Barreto said. “Mitt Romney, of course,did very poorly among Latinos. Now, Mitt Romney looks like a nice guy compared to what Donald Trump is saying.”

Moreover, the growth in the Latino electorate is being powered by millennials, who will boost the eligible voting pool for years to come.

While turnout among Latino voters is notoriously low, Democrats and allied groups have beefed up a strong presence in critical swing states -- Florida, Nevada, Virginia, North Carolina and others -- to push them to the polls.

“This is not just about now, it’s about 20 years in the future,” said Mark Hugo Lopez, director of Hispanic Research at Pew. “Where will the Latino vote go after the next election cycle? Will it be like a California in the 1990s?”

Florida Sen. Marco Rubio, whose candidacy offered the party perhaps its best chance this cycle to turn a new page with Latinos, said that Trump’s approach to these issues “certainly doesn’t help.”

But Rubio is also among those who believe the party can right itself and mend relations with a new message.

“If [Trump] doesn’t win, there’ll be a new nominee in four years that will define what the party is,” Rubio said in a brief interview.

Many Republicans remain hopeful that Trump’s popularity on economic and national security issues will overshadow his impolitic comments on race.

They note that Latinos are not a monolithic voting bloc, but a diverse electorate made up of Mexicans, Cubans, Puerto Ricans and Central and South Americans, who bring varied backgrounds into the voting booths. Now, as in years past, Republicans have argued that many Latinos naturally align with the GOP, particularly on faith issues.

“Obviously, what Trump is saying antagonizes Hispanics, but it doesn’t mean the Republican Party will lose the vote for a generation,” said Alfonso Aguilar, a former Bush administration official who is now president of the Latino Partnership for Conservative Principles. “This is dependent on the rhetoric the Republicans choose.”

However, Aguilar acknowledged that his informal talks with Trump aides have left him concerned that the campaign is not doing enough Latino voter outreach.

“Some will disagree with me, but if Mr. Trump were to moderate his tone, clarify some of his positions, pivot to the center, he could be more competitive with Latinos,” Aguilar said.

Others insist the broken relationship between Republicans and Latinos runs deeper than simple slights, such as Trump tweeting a picture of himself eating a taco bowl on Cinco de Mayo with the caption, “I love Hispanics!”

“It’s possible they could undo the damage, but it will take miraculous healing power,” said Pitney, a former GOP policy aide. “Republicans will have to learn the act of contrition in Spanish.”

lisa.mascaro@latimes.com

Follow on Twitter @LisaMascaro