PASADENA, Calif. -- Immigration policy hasn't yet become the most talked-about issue among the Democratic presidential field, but four candidates came here Friday to blast President Donald Trump's record on the issue and present their own plans.

California's early March primary next year makes it a prime target for candidates to pick up electoral votes and immigration could become a front-burner issue here. The issue, and the voters who care most about it, attracted U.S. Sens. Kamala Harris and Bernie Sanders, former Housing and Urban Development Secretary Julian Castro, and Washington state Gov. Jay Inslee.

The candidates spoke to a crowd at the Unity and Freedom Presidential Forum, which brought together three activist groups on the same weekend many candidates are in California for the state party's annual convention.

Each candidate knocked Trump on immigration-related issues ranging from the building of a wall along the United States' southern border to splitting up immigrant families coming through Mexico. While other candidates were more measured in their criticism, Sanders called Trump a racist in light of his policies.

"We have a president who is a racist, who is a pathological liar, who thinks he can win by dividing the American people by the color of our skin or where we were born," Sanders. "We are going to do exactly the opposite. We are going to bring our people together."

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More:Democratic presidential candidates offer few details on immigration plans so far

Both Sanders, I-Vt., and Harris, D-Calif., vowed to protect from deportation not only those undocumented immigrants who were brought to the U.S. as children, but their parents as well.

Referring to the Deferred Action for Childhood Arrivals program, which has shielded those roughly 800,000 undocumented immigrants, Harris said "DACA recipients have parents who deserve a path to protection." The Trump administration has tried to end the DACA program but has been thwarted by the courts. The administration is currently appealing the rulings.

Harris promised to reverse "backward, hate-driven policies," including revoking the ban on immigration from some Muslim-majority nations. She also called for the federal government to quit contracting with private detention facilities to house immigrants.

Castro, who also is the former mayor of San Antonio, Texas, argued the U.S. needs more immigration, not less in light of declining birth rates.

"We need a young, vibrant workforce," Castro said.

He said border crossings should be decriminalized and the federal government should stop relying on local law enforcement to identify undocumented immigrants for federal authorities.

Inslee said the anger against Trump needs to be channeled into positive energy. He also said local law enforcement officers should not be called upon as "mini-ICE agents," referring to Immigration and Customs Enforcement.

While the other candidates stuck to immigration, Sanders broadened his message to hit his other core issues, including climate change, cutting college costs, universal health care and ending the war on drugs by legalizing marijuana. "I am not smoking anything today," he said to laughs.

The forum was sponsored by the CHIRLA Community Action Fund, Community Change Action and FIRM Action.