BERKELEY — Lt. Gov. Gavin Newsom is maintaining a clear edge over other declared candidates in the 2018 California governor’s race, according to a new poll by UC Berkeley’s Institute of Governmental Studies.

Newsom was preferred by 28 percent of registered voters when paired with four other declared candidates. John Cox, a Republican venture capitalist from San Diego County, was the choice of 18 percent of voters. Trailing were the three other Democrats who have jumped into the race: former Los Angeles mayor Antonio Villaraigosa (11 percent), state Treasurer John Chiang (8 percent) and former state schools superintendent Delaine Eastin (3 percent).

About one in three voters — and nearly half of independent voters — said they did not yet have a preference in the race.

Mark DiCamillo, the poll’s director, attributed Newsom’s lead at this early stage to name recognition.

“This is a heavily Democratic state, he’s very popular among the Democrats and I think a big part of that he is familiar to them — and what most Democrats know about Newsom they tend to like,” the veteran pollster said.

Newsom also polled well when five other possible candidates were added to the mix. He was favored by 24 percent of voters. Cox and fellow Republican Kevin Faulconer, San Diego’s mayor, were both favored by 11 percent of voters, followed by Los Angeles Mayor Eric Garcetti, a Democrat who was favored by 9 percent of voters; Villaraigosa (7 percent); Chiang (6 percent); billionaire environmentalist Tom Steyer, a Democrat (4 percent); state Senate leader Kevin de León (3 percent), a Democrat; former Democratic state controller Steve Westly and Eastin (2 percent each).

The poll showed that Newsom’s sizable lead comes from strong support in the Bay Area and among registered Democrats statewide. Cox’s support comes primarily from fellow Republicans. And Villaraigosa’s strongest support comes from fellow Latino voters.

Political analysts say that Newsom, a former San Francisco mayor, got a big jump-start by declaring his candidacy in February 2015. A series of polls have consistently shown him at the top of the pack since then. Villaraigosa entered the race two days after Donald Trump was elected president in November.

Villaraigosa has name recognition in Southern California, but “not so much in Northern California, where a lot of the Democratic vote would come from,” said Jack Pitney, a professor of politics at Claremont McKenna College in Southern California. “Also, he’s been out of office for several years now — and Californians have pretty short memories when it comes to politics.”

Garcetti’s better performance in the poll is likely a result of his recent overwhelming reelection as L.A. mayor, DiCamillo said.

“He is now among the second tier of candidates behind Newsom,” DiCamillo said. “Newsom, among the Democrats, is clearly in a tier by himself. The others are kind of vying for second.”

Under California’s unusual primary system, the top two vote-getters advance to the general election regardless of party affiliation. So it’s not unusual for two Democrats or two Republicans to run against each other in the November election.

Cox, the San Diego County venture capitalist, announced his candidacy earlier this month, condemning the state’s high poverty rate, high taxes and unfunded pension liabilities.

“There are two Californians — the one we have, and the one we could have,” he said in a statement. “The California we have is in trouble, and we need to do something about it.”

Cox has said he plans to seed his campaign with $1 million of his own money.

Faulconer is viewed as a moderate Republican. He refused to endorse Trump before the November election.

Newsom has taken a more aggressive stance on Trump, regularly taking to Twitter to blast the president’s actions on everything from immigration to the environment. Pitney said that approach also has helped push Newsom to the top of the list as a candidate.

“Given that Trump is about as popular in this state as dysentery, being anti-Trump is nothing but a plus in the gubernatorial race,” said Pitney, a former GOP official.

Neither of the Republicans is well known by voters, and they could split the vote if they both end up running, resulting in a “Democrat on Democrat” general election, Pitney said.

The poll’s findings are based on a survey of 1,000 registered voters taken March 13 through March 20. The poll was administered online in English and Spanish by YouGov, an international market research firm. The results have a margin of error of plus or minus 3.6 percent.

Pitney cautioned that nothing is set in stone with the primary still more than a year away.

“It’s early and the numbers could shift a great deal depending on events, depending on the kinds of campaigns that people run,” Pitney said. “This is the first word. It’s not the last.”