SACRAMENTO (REUTERS) - California voters on Tuesday (Sept 14) were deciding whether to recall Governor Gavin Newsom in a special election that will test the power of a Republican Party still dominated by former US President Donald Trump in a deeply Democratic state.

Newsom - a first-term governor and former lieutenant governor and San Francisco mayor - is fighting for his political future in only the second gubernatorial recall election in state history in 55 attempts. The latest opinion polls show him favoured to retain his job.

Mail-in voting began nearly a month ago, with in-person voting taking place on Tuesday and the polls closing at 8pm PDT, or 11pm EDT (11am Singapore time).

The campaign to oust the Democratic governor began with a conservative Republican group and gained steam during the pandemic. Conservatives, angered by Newsom's liberal policies on LGBTQ rights, immigration and crime, also became infuriated by his decision to close schools and require masks and vaccinations against Covid-19.

"His policies on Covid have been disastrous. He's not fighting for freedom of choice, which is what Americans want,"said Michael Conners, 54, a Republican handyman wearing a Trump hat to a polling place where he voted to recall Newsom in Carlsbad, on the San Diego County coast.

Another voter in favour of recalling the governor cited Newsom's pandemic response and its impact on small businesses.

"I'm a small business owner and my son was out of school almost a year," said Republican hair salon owner Taylor Livesley, 31. "I don't believe in vaccines being mandated."

The removal of Newsom would likely embolden Republicans in one of the country's most liberal states and set off alarms among Democrats, coming just over a year before the 2022 elections that will decide control of Congress.

Recall also could mean the end of Newsom's political ambitions, widely believed to include possible runs for the US Senate or the presidency.

Whether Newsom survives the recall or is replaced, the next gubernatorial election will take place in November 2022.

The latest opinion polls showed Newsom with strong support.

In a survey released on Friday by the Institute of Governmental Studies at the University of California, Berkeley, 60.1 per cent of likely voters said they favoured retaining the governor and 38.5 per cent opposed him staying in office.

Democrats have returned twice as many ballots as Republicans so far in a four-week early voting period, state data showed.

One voter who supports Newsom said she feared a Republican victory could weaken voting rights and abortion rights or reduce the state's minimum wage of $14 per hour, nearly twice the federal minimum of US$7.25.

"We could see changes like what's happening in Texas," said Katie Van Note, 27, a dance instructor who voted in Oceanside, just north of Carlsbad, and describes her politics as left-leaning.

Polls favor Newsom

Newsom's poll numbers have improved from earlier this summer, when polls showed so few Democrats were planning to vote that his job was in jeopardy in a state where Republicans make up less than a quarter of the electorate.

The polls "changed Democrats' mindset from sitting back on the couch to saying, 'This is something we've got to do,'" said Paul Mitchell, whose firm Political Data Intelligence analyzed state ballot return information.

Under California's recall system, voters are asked to vote "yes" or "no" on whether to recall Newsom. If more than 50 per cent of voters say Newsom should be recalled, then the candidate with the most votes on the second question - even if less than a majority - automatically replaces him for the remainder of his four-year term.

Republican radio host and Trump supporter Larry Elder leads the slate of 46 replacement candidates. Elder, who has high visibility from his frequent appearances on conservative Fox News, has vowed to remove requirements for vaccines and mask wearing.

Seven of eight randomly selected Republican "yes" voters in Carlsbad and Oceanside said they had voted for Elder.

"I love Larry Elder. He has good ideas and I trust him highly," said Republican voter Nancy Gruba, 69, a physical therapist in Carlsbad.

In the Berkeley poll, Elder was supported by about 38 per cent of those likely to vote on a replacement. Kevin Paffrath, a Democrat and YouTube host, received 10% support, followed by former Republican San Diego Mayor Kevin Faulconer at 8%.

Former gubernatorial nominee John Cox and Republican reality TV star Caitlyn Jenner also are on the ballot.

Results from the recall may not be immediately known.

Mail-in ballots can be postmarked as late as Tuesday.

Mitchell said that, for Newsom to be recalled, Republicans would need overwhelming turnout for in-person voting on Tuesday, and Democratic participation would need to slow way down.

The last time a Republican took the helm of the overwhelmingly Democratic state was in 2003, when actor Arnold Schwarzenegger, a Republican, was chosen in a recall to replace Democrat Gray Davis.

Newsom ramped up his outreach to Democrats in recent weeks, including appearing with President Joe Biden at a rally on Monday night. Newsom has tied the recall effort to Trump and said Elder would impose conservative policies on abortion, immigration, gun rights and other issues.