It wasn’t a message many of the California Democratic Party convention delegates were eager to hear.

Former Colorado Gov. John Hickenlooper, one of 14 presidential candidates speaking to the convention in San Francisco, styles himself as a moderate. When he got his turn Saturday, he told the delegates in the Moscone Center, “If we want to beat Donald Trump and achieve big progressive goals, socialism is not the answer.”

He smiled as a sustained round of boos rained down.

Moments later, he broke with his prepared remarks to add, “If we’re not careful, we’re going to end helping to re-elect the worst president in American history.”

He was booed a second time when he said the country should strive for universal health care without eliminating private insurance.

Hickenlooper was followed by Washington Gov. Jay Inslee, who received a big reaction when he opened with the line, “I am the governor who doesn’t think we should be ashamed of our progressive values.”

In an interview after his speech, Hickenlooper said he did not come to San Francisco hoping to be booed.

“But I was prepared for it,” he said. “I understood that we’re staking out a position that with some people is unpopular.

“I would argue that it certainly was not the majority,” he added, noting that he got 50 selfie requests as he was leaving the convention hall.

Hickenlooper is walking a fine line, trying not to completely alienate the liberal wing of the Democratic Party that is fired up to defeat Trump.

He called himself a “pragmatic progressive” in the interview, pointing to his record as mayor of Denver, where he expanded pre-kindergarten to all 4-year-olds, and Colorado governor, when he signed a universal background check law for gun purchases.

But he also reiterated that “as a party and as individual candidates, we have to say loudly and clearly that we’re not socialists, that we don’t stand for socialist values,” Hickenlooper said.

He said he would win over liberal voters by showing them that “you can get to these big, progressive goals” through collaboration with the business community.

So, will a campaign advertisement featuring the boos be coming to a television near you soon, à la Sen. Dianne Feinstein? After being jeered at the 1990 California Democratic Party convention for supporting the death penalty, she made the moment the centerpiece of a TV spot during her unsuccessful run for governor that fall.

Hickenlooper laughed at the idea, though he didn’t he rule it out: “You have to talk to my staff.”

Alexei Koseff is a San Francisco Chronicle staff writer. Email: akoseff@sfchronicle.com. Twitter: @akoseff