Bernie Sanders and Kamala Harris dueled Friday over Hispanic votes in California, a central front in the nation’s immigration battle where Latinos represent the state’s largest ethnic group. As the nation’s most populous state, California holds a trove of 2020 delegates that are being eagerly sought by Democratic presidential rivals. The appearance of the two prominent contenders at a forum organized by immigrant rights activists kicked off several days of intense campaigning in the state, which will culminate at a state Democratic convention in San Francisco where 14 candidates are scheduled to appear. Harris elicited a burst of applause when she told the group that she was a proud daughter of immigrants from India and Jamaica, then promised that if elected she would work for comprehensive immigration reform in her first 100 days in office. She also promised to end the “hate-driven” policies of the Trump administration, including the so-called travel ban. “This is a nation that was founded by immigrants,” she said at one point. Any delay, she said, brings more human suffering when families are separated or treated unjustly. Sanders took the stage to chants of “Bernie, Bernie.” He opened his remarks by labeling President Donald Trump a “racist” who was trying to win re-election by dividing Americans by skin color and where they were born. If elected, “we are going to do exactly the opposite,” Sanders said. Americans, he said, want immigration reform and a path to citizenship for the millions of people who entered the U.S. illegally. He promised to bring an administration to Washington that “represents the needs of the working people of this country,” not just the wealthy. The Hispanic vote has become increasingly important in strongly Democratic California, particularly in a Democratic presidential primary. California was once a reliably Republican state in presidential elections, but a surge in immigrants transformed the state and its voting patterns. The number of Hispanics, blacks and Asians combined has outnumbered whites in the state since 1998. Meanwhile, new voters, largely Latinos and Asians, lean Democratic. The last Republican to carry the state in a presidential election was George H.W. Bush, in 1988. The candidates each tacked to similar themes, including criticizing the Trump administration’s immigration policies and enacting comprehensive reform. However, candidates can expect a skeptical look from many voters, Latino and otherwise, who have heard promises from both parties for years about immigration reform that never arrived. When asked how she would assure Hispanics that she wasn’t another candidate with an empty promise, Harris told reporters, “By pointing to my record” as a senator and former state attorney general. Sanders, too, said he would introduce a comprehensive immigration plan shortly after taking office. He also said he would expand an Obama-era program that shields young immigrants from deportation. “This is a promise that will be kept,” the Vermont senator said. Lisa Luther, who attended a raucous Sanders rally earlier in the day at a nearby convention center, said she was confident the senator could deliver on immigration reform when other Democrats have failed. Luther, who once worked as a chef, said she has seen firsthand the struggles of immigrants who worked beside her. Sanders “will not let it fall by the wayside,” she said. “It’s been so prevalent in … his campaigns.” Julian Castro, a former Obama administration housing secretary, spoke to the crowd about his Mexican heritage and argued that new immigrants are necessary to maintain economic vitality. That’s especially important, he said, as Baby Boomers grow old and draw on Social Security. New workers mean more money to support the federal retirement system, he said. Castro is one of two candidates in the crowded Democratic field that have released detailed, written policies addressing the future of the immigration system, as the issue has been overshadowed on the campaign trail by health care, gun violence and reproductive rights. “It would be economic suicide not to have them,” he said of immigrants. Democratic hopeful Jay Inslee, who has pledged to make combating climate change the top national priority, faulted Trump for ignoring a global warming crisis that is influencing immigration and creating “climate migrants.” The Washington governor said at the forum Friday that a plan is needed to fight global warming while helping those driven from their homes by a changing climate. The Trump administration has proposed its own overhaul that would bolster border security while creating a “merit-based” immigration system prioritizing people with in-demand job skills, rather than relatives of people already in the U.S. But that was largely seen as symbolic, and the president has repeatedly returned to his calls for extending the U.S.-Mexico border wall and imposing stricter immigration policies. The forum was sponsored by the groups FIRM Action, Community Change Action and CHIRLA Action Fund.