A sizable majority of Californians support slapping a moratorium on hydraulic fracturing, according to a new poll released Thursday.

Photo: The Chronicle

The poll, commissioned by the Sierra Club and the Natural Resources Defense Council, found that 68 percent of Californians support a bill pending in Sacramento that would halt fracking until the state has a chance to study its safety. The bill — SB1132 from Sens. Mark Leno, D-San Francisco, and Holly Mitchell, D-Los Angeles — is under consideration in the Senate Appropriations Committee and faces a May 30 deadline to win full Senate approval.

Although voters tend to split along party lines on oil and energy issues, the poll found support for a fracking moratorium across California’s political spectrum. Fully 78 percent of Democrats back a moratorium, a position shared by 74 percent of independents and 51 percent of Republicans.

The poll also found that most respondents — 76 percent — were familiar with fracking, which uses pressurized water, sand and chemicals to crack open subterranean rocks containing oil or natural gas. Among those who know about the oil extraction technique, 53 percent oppose it outright. A larger number, 59 percent, oppose “acidizing,” which employs powerful acids to loosen oil-bearing rocks.

Oil companies have used acidizing and fracking in an effort to tap California’s Monterey Shale, an immense geologic formation thought to be packed with crude.

But so far, California hasn’t seen the kind of oil-shale production boom taking place in North Dakota and Texas. And on Wednesday, the federal government slashed by 96 percent its estimate of the amount of oil that current drilling technology can pry from the Monterey Shale. That dramatic revision could lend momentum to the push for a moratorium.

Conducted by the firm Fairbank, Maslin, Maullin, Metz & Associates, the poll surveyed 807 Californians by phone between May 13 and May 15. The margin of error is 3.5 percent.