Story highlights Lessons for Trump in the effect of California's Prop 187

Steep decline of registered Republicans in California after anti-immigrant measure

Los Angeles (CNN) After clinching the Republican nomination with his divisive rhetoric on immigration, some thought Donald Trump would soften his tone, particularly as he wrapped up his primary campaign in the most populous and diverse state in the nation.

But the imperative to broaden his appeal among Latinos voters has seemed far from his mind. His California events have been disrupted by pro-immigration protesters who he belittles. He recently hurled insults at the California judge overseeing the fraud case involving Trump University, calling him a "Trump hater" and raising questions about his Mexican heritage. Outside his recent San Diego rally, protesters waved Mexican flags and shouted "F--- Trump."

It is yet another reason Republicans are worried about the potential long-term damage that Trump has inflicted on the GOP's image, and their efforts to reach out to younger Latino and minority voters who will be increasingly critical with each election cycle.

The crowds of protesters and clashes outside Trump's rallies in California have served as an eerie reminder of what happened to Republicans here in California after they got behind Proposition 187, the 1994 ballot measure that would have barred immigrants from getting basic state services.

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