A ballot measure to raise taxes on multimillionaires to subsidize zero-emission vehicle programs, which has pitted Gov. Gavin Newsom against his own political party and the ride-sharing company Lyft, is narrowly favored by voters but remains in jeopardy.

A new poll from the UC Berkeley Institute of Governmental Studies, co-sponsored by The Times, found 47% of likely voters favored Proposition 30 while 41% were against it, with support dipping slightly since September.

Berkeley IGS poll director Mark DiCamillo said the proposition’s failure to win support from more than 50% of likely voters, even with an endorsement from the California Democratic Party and $44 million already spent promoting the measure, indicates that it could falter in the final week before the November election.

“What it says to me is that over the past month there hasn’t been any movement toward the ‘yes’ side,” DiCamillo said. “That’s significant in a ballot proposition. It’s got to get over 50% to pass, and most undecided voters vote no. So it’s gonna be close.”

The poll also found:

• Two ballot measures aimed at expanding sports betting are trailing badly and likely to lose.

• A measure to amend the state constitution to bolster abortion rights is on track for a solid victory.

• A referendum to ban flavored tobacco products is also on track to win.

• Newsom’s reelection appears in solid shape.

Proposition 30 was trailing 50%-43% among voters surveyed who had already cast their ballots, according to the poll, which was conducted from Oct. 25-31.

At stake in the fight over the measure is whether wealthy taxpayers will pick up part of the cost of shifting a large part of the state’s vehicle fleet from gasoline to electric power.

The proposition would require wealthy Californians to pay an additional 1.75% in state income taxes on annual earnings above $2 million starting in 2023. The tax increase would raise $30 billion to $90 billion over the next 20 years, with 80% of the money being used to subsidize the purchase of electric vehicles and set up charging stations and other infrastructure. The remaining 20% would be set aside for wildfire suppression and prevention.

Supporters of Proposition 30, whose largest financial donor is Lyft, the ride-hailing company, call it the “clean air initiative.” They’ve run ads touting the measure as an essential way to combat climate change, reduce car emissions and harmful pollution and prevent catastrophic wildfires.

Along with Lyft, which has contributed more than $45 million to the campaign, the measure is backed by the state Democratic party, the American Lung Assn., the Natural Resources Defense Council and the State Building and Construction Trades Council.

Newsom, who has become the de facto opposition campaign, criticized the measure as a scheme by Lyft to rake in “corporate welfare” and help the company meet a state mandate for ride-hailing companies to convert most of their fleets to electric vehicles by 2030.

“Prop. 30 has been advertised as a climate initiative. But in reality, it was devised by a single corporation to funnel state income taxes to benefit their company. Put simply, Prop. 30 is a Trojan horse that puts corporate welfare above the fiscal welfare of our entire state,” Newsom says in an ad criticizing the measure.

Newsom is the biggest financial backer of the opposition campaign, contributing more than $1.5 million from his gubernatorial reelection fund. Other major donors to the opposition include Netflix CEO Reed Hastings, venture capitalists Bruce Dunlevie, Michael Moritz and David Marquardt, former Wells Fargo Chief Executive Richard Kovacevich and former Oakland Athletics owner Lewis Wolff.

Pomona College political scientist Sara Sadhwani said Proposition 30 creates a dilemma for many California voters, pitting support for transitioning to a clean energy economy against cynicism about a company using that support to benefit financially. Voters may also be weary of proposed tax increases at a time when they are struggling with high inflation and gasoline prices, she said.

“Californians are very concerned about the state of the economy,” Sadhwani said. “While it might be tempting to tax the rich, placing any additional financial burdens in this economic climate becomes a really tough choice for voters, even if it wouldn’t impact them directly.”

The picture was much clearer on the measures to legalize sports betting in person and online.

Despite more than a half billion dollars pouring into the campaigns for Propositions 26 and 27, both face strong opposition.

Proposition 26 would allow in-person sports betting at tribal casinos and horse racing tracks. It was trailing 53%-30% among likely voters, the poll found.

Leaders of four of California’s most successful Native American tribes with gaming interests are the original proponents of Proposition 26, which would impose a 10% tax on sports betting to fund gambling addiction treatment and enforcement programs.

Proposition 27, which would allow online sports wagering, fared even worse — 22% of likely voters in support and 64% opposed.

Proposition 27 is funded by gambling corporations, including sports gaming companies DraftKings and FanDuel. If the measure passed, tribes and gambling companies with sports betting licenses would pay 10% of their take from sports bets each month to the state, after subtracting some expenses and losses, to fund programs for homelessness and gambling addiction.

Campaigns for the two competing measures have aired a constant barrage of attack ads against one another. As a result, voters probably are confused about the differences between the dueling propositions, DiCamillo said.

By contrast, Proposition 1, the proposed amendment to the California Constitution to explicitly protect the right to an abortion, was favored by 64% of likely voters in California, compared to 27% who opposed it.

Proposition 31, a measure that would ban the sale of most flavored tobacco products, was supported by 58% of those surveyed and opposed by 32%.

In the race for governor, Newsom leads his Republican challenger, state Sen. Brian Dahle, 58% to 37%, among likely voters. Only 4% were undecided.

Newsom’s strongest bases of support were in the Los Angeles County and the San Francisco Bay Area, California’s two largest population centers. Dahle, a conservative Republican from the Northern California town of Bieber, had a slight edge in Orange County and the Inland Empire, along with the San Joaquin Valley.

Newsom’s dominance in the race was no surprise given Dahle’s lack of name recognition in California and Newsom’s trouncing of the Republican-led recall attempt last year, Sadhwani said.

“He had overwhelming support and a very clear mandate when he won the recall election last year,” Sadhwani said. “You can continue to see him riding the wave of that. We haven’t even seen him going out and doing any extensive campaigning.”

The Berkeley IGS poll was conducted online Oct. 25-31 among 7,602 California registered voters, including 5,972 who were deemed likely to vote in the November election. The sample was weighted to match census and voter registration benchmarks. Because of weighting, precise estimates of the margin of error are difficult, but the results are estimated to have a margin of error of approximately 2 percentage points in either direction for the likely voter sample.

This story originally appeared in Los Angeles Times.