"History suggests that when voter support for a controversial ballot initiative like repealing the death penalty remains below 50 percent, its passage is uncertain, even when leading in the polls, a press release accompanying the poll explained.
Fifteen percent of poll respondents said they were undecided.
When Californians head to the polls in November, they will face a second referendum on capital punishment. That measure would limit the legal appeals of criminal defendants who are sentenced to die.
The Field poll revealed that 42 percent of respondents remain undecided on the second measure, while 35 percent said they were inclined to vote "yes" and 23 percent said they would likely vote "no".
Currently, 19 US states along with Washington, DC have laws prohibiting capital punishment.
