Gavin Newsom leading candidate in ’18 governor’s race, poll finds

FILE- In this May 11, 2016 file photo California Lt. Gov. Gavin Newsom speaks during a meeting of the University of California Board of Regents in Sacramento, Calif. An online magazine opinion piece attributed to California Lt. Gov. Gavin News contains at least one paragraph that largely originally appeared on the website of the National Center for Lesbian Rights. (AP Photo/Rich Pedroncelli, File) less FILE- In this May 11, 2016 file photo California Lt. Gov. Gavin Newsom speaks during a meeting of the University of California Board of Regents in Sacramento, Calif. An online magazine opinion piece attributed ... more Photo: Rich Pedroncelli, Associated Press Photo: Rich Pedroncelli, Associated Press Image 1 of / 69 Caption Close Gavin Newsom leading candidate in ’18 governor’s race, poll finds 1 / 69 Back to Gallery

SACRAMENTO — An early look at California’s 2018 gubernatorial election shows Lt. Gov. Gavin Newsom leading the field of declared and likely candidates to replace Gov. Jerry Brown, a Field Poll released Monday found.

Twenty-three percent of the state’s registered voters favor the former San Francisco mayor, a Democrat who is running for the seat. San Diego Republican Mayor Kevin Faulconer came in second, with 16 percent of voters saying they would like to see him elected governor. Fresno Republican Mayor Ashley Swearengin placed third among preferred candidates with 11 percent. Faulconer and Swearengin have been rumored to be considering a run but have not yet jumped into the race.

Other likely and declared candidates include Los Angeles Mayor Eric Garcetti, 7 percent; former Los Angeles Mayor Antonio Villaraigosa, 6 percent; environmentalist Tom Steyer, 5 percent; Secretary of State Alex Padilla, 4 percent; state Treasurer John Chiang, 2 percent; and former state Controller Steve Westly, 1 percent.

A quarter of voters said they are undecided in the 2018 race to replace the termed-out Brown.

“It will be a very interesting race,” said Field Poll Director Mark DiCamillo. “This will be the next generation of California politics in the state.”

The poll included likely candidates as well as those who have announced they are running. Newsom jumped into the race in 2015. Chiang announced his bid in May, former state schools Superintendent Delaine Eastin jumped into the race earlier this month, and Villaraigosa officially became a gubernatorial candidate last week.

Eastin announced her campaign after the poll was conducted or she would have been included, DiCamillo said.

A voter’s party registration was one of the biggest indicators of whom that voter will support, the poll found. Newsom was the pick of one-third of Democrats and 2 percent of registered Republicans.

When candidates were identified with their party affiliation, as they are on the ballot when people cast their votes, Republicans favored Faulconer 42 percent to Swearengin’s 31 percent.

But when party affiliation was left out, support for Faulconer and Swearengin dramatically dropped.

“What’s interesting is if you don’t mention party, the two Republicans go way down because Republicans can’t identify who the Republicans are,” DiCamillo said.

DiCamillo said it will be interesting to see whether the race includes two Democrats like last week’s U.S. Senate race between state Attorney General Kamala Harris and Orange County Rep. Loretta Sanchez. DiCamillo said Harris’ election to Sen. Barbara Boxer’s seat showed that when a Democrat faces another Democrat, many Republicans opt to not vote.

“Many Republicans sat on their hands in that race,” he said.

The Field Poll surveyed 1,200 registered voters online between Oct. 25-31 in English and Spanish, depending on the voter’s preference. Because the poll was conducted online using an opt-in panel, there is no sampling error estimate.

Melody Gutierrez is a San Francisco Chronicle staff writer. Email: mgutierrez@sfchronicle.com Twitter: @MelodyGutierrez