California is facing new challenges, and the next governor will be forced to make major changes to prepare the state for a very different future, Lt. Gov. Gavin Newsom, a Democratic candidate for governor, said in San Francisco Thursday.

Health care, an aging population, climate change and the threat automation poses to existing jobs are just a few of the problems facing the state in coming years, the former San Francisco mayor told about 200 people at a downtown talk at the Public Policy Institute of California.

“I could go on and on and on ... about setting audacious goals the next governor has to deliver,” Newsom said, to laughter from the crowd.

But as governor, Newsom said, he would be willing to make the hard choices needed.

“I have no interest in failing more efficiently,” he said. “I have no interest in playing in the margins.”

His support for single-payer health care is one of the things that sets him apart from the other candidates for governor, Newsom said. The existing health care system is bankrupting the state, and “we can’t afford to not do something radically different.”

The lieutenant governor argued that a single-payer system without the profit factor and the marketing expenses that mark the current private insurance system can’t help but be cheaper.

Putting a single-payer plan into operation — and paying for it — will require “leadership and creativity,” as well as a consensus on what California’s priorities should be, Newsom said.

“I know my opponents want to exploit this for political purposes,” complaining that the arguments for single-payer are little more than wishful thinking bolstered by fudged numbers, Newsom said. “But it’s not snake oil to face a problem head-on.”

Newsom announced his run for governor in February 2015, just weeks after being sworn in for a second term as lieutenant governor. He’s been the front-runner ever since in a race that’s beginning to split along regional and ethnic lines.

An online USC Dornsife/Los Angeles Times poll released Thursday showed Newsom with the support of 31 percent of registered voters. He was followed by former Democratic Los Angeles Mayor Antonio Villaraigosa with 21 percent, Orange County GOP Assemblyman Travis Allen with 15 percent, Democratic state Treasurer John Chiang at 12 percent, GOP businessman John Cox with 11 percent and Democratic former state schools chief Delaine Eastin at 4 percent.

Newsom outpolled Villaraigosa, 53 percent to 6 percent, in the Bay Area, while most of the former Los Angeles mayor’s support was in Southern California. Villaraigosa also has support from about two-thirds of the state’s Latino voters.

With Gov. Jerry Brown in Europe talking about climate change, Newsom introduced himself as the state’s acting governor. But because he and the governor have not always seen eye to eye, Newsom was forced to walk a narrow line, praising his popular boss but also suggesting that a Newsom administration would be very different.

At one point, for example, Newsom said that “with all due respect,” as a citizen and lieutenant governor he was frustrated that the state and, by inference, Brown “ceded some of the federal immigration conversation to (former Arizona Gov.) Jan Brewer and (federal Secretary of Energy) Rick Perry” — both avid supporters of President Trump’s proposed immigration crackdown.

He also suggested that Brown has done a much better job setting goals for such issues as climate change, water storage and affordable housing than he has in actually meeting them.

On high-speed rail, one of the governor’s signature issues, Newsom argued that while he supported the original plan, he has real concerns with the proposed rail system as it’s now proposed.

“Let’s be honest with people,” he said. “It’s not the vision, it’s the application of the vision.”

That ratio of talk to action is not unique to Brown, Newsom admitted.

“I get it,” he said. “When I was mayor, I was very good at establishing goals ... for (his successor, current San Francisco Mayor) Ed Lee.”

But Newsom also had plenty of praise for Brown and even a bit for Trump, noting that the president didn’t play politics with the Oroville Dam repairs and the Wine Country fire response.

Brown has balanced resistance to much of Trump’s agenda with an ability to work with the president on the needs of the state.

“I’ve studied him,” Newsom said, adding that Brown also has proved “you don’t have to be profligate to be progressive.”

As governor, however, Newsom said he would be an agent of serious change for a state that soon will look very different than it does today.

“I’m not timid,” he said. “If you want timid, I’m not your guy.”

John Wildermuth is a San Francisco Chronicle staff writer. Email: jwildermuth@sfchronicle.com Twitter: @jfwildermuth