2020 Democratic presidential candidate John Hickenlooper booed at a California convention

Former governor of Colorado and 2020 Democratic candidate John Hickenlooper says socialism is not the answer to beating Donald Trump, and is booed by the audience.

UNITED STATES (REUTERS) - Fifteen of 24 Democratic candidates running for the post of United States president are trying to drum up support, CBS reported, with 14 of them making speeches at some point this weekend.

The cluttered field does make some delegates nervous.

Former governor of Colorado John Hickenlooper was among the speakers.

"If we want to beat Donald Trump and achieve big progressive goals, socialism is not the answer," he told the crowds, who responded with boos.

But Mr Hickenlooper continued, saying, "I was re-elected in a purple state in 2014, one of the worst years for Democrats in a quarter-century.

"If we're not careful, we're going to end up helping to re-elect the worst president in American history."