LOS ANGELES, CALIFORNIA - OCTOBER 04: Democratic U.S. presidential candidate and former Vice President Joe Biden pauses while speaking at the SEIU Unions for All Summit on October 4, 2019 in Los Angeles, California. Eight Democratic Presidential candidates were scheduled to speak today and tomorrow at the summit. The presidential primary in California will be held on March 3, 2020. (Photo by Mario Tama/Getty Images) Foto: Mario Tama/Getty ImagesLOS ANGELES, CALIFORNIA - OCTOBER 04: Democratic U.S. presidential candidate and former Vice President Joe Biden pauses while speaking at the SEIU Unions for All Summit on October 4, 2019 in Los Angeles, California. Eight Democratic Presidential candidates were scheduled to speak today and tomorrow at the summit. The presidential primary in California will be held on March 3, 2020. (Photo by Mario Tama/Getty Images) Foto: Mario Tama/Getty Images