The San Francisco convention became a window into the forces at work in the Democratic Party as it seeks to recover from Trump's populist-fueled victory in 2016.
United States (U.S.) Senator Bernie Sanders on Sunday called on California Democrats to unite against Donald Trump, kicking off the 2020 presidential campaign, by calling Trump "a racist, a sexist, a homophobe and a religious bigot" in a speech capping off the state's Democratic convention.
The Convention drew fourteen of the 24 candidates to make their case before 5,000 delegates, guests and press in the most populous - and most heavily Democratic U.S. state.
The party's left-leaning delegates greeted Sanders and liberal U.S. Senator Elizabeth Warren.
However, former U.S. representative from Maryland John Delaney, who was the first Democrat to enter the 2020 race, drew boos when he addressed the convention on healthcare policy.
Other moderates were also booed for rejecting the idea of a universal public health care system, or Medicare for All.
Former Vice President Joe Biden, who leads Sanders in polls for the Democratic nomination in California and nationwide, did not attend the convention, drawing barely-veiled criticism from Sanders.
Sanders noted that the 14 candidates who addressed the convention, as well as some who had "chosen for whatever reason not to be in this room," offer a variety of ways to approach a campaign against Trump. But Sanders rejected the centrist approach favored by Biden and some other candidates.
On issues like health care, pharmaceutical prices and climate change threatening the country, Sanders stated that "there is no middle ground."
Addressing concerns among some Democrats that a moderate would be more electable than a fiery progressive, Sanders said such an approach would not generate the enthusiasm needed to defeat Trump.
"We will not defeat Donald Trump unless we bring excitement and energy into the campaign and unless we give millions of working people and young people a reason to vote and a reason to believe that politics is relevant to their lives," Sanders added.
According to a Gallup poll released last week, more people in the U.S. believe socialism would be a good path for the country to take, as socialism-supporters lost by only a small percentage to those U.S. citizens who still oppose the political ideology but in lower proportions than ever before.
California, which will send nearly 500 delegates to the party's nominating convention next year, took on new heft for the 2020 campaign after moving its nominating election from March to June.
Democrats hold all statewide elective offices in the state and dominate both houses of the legislature.