Obama's support surged by 13 points in the last month, according to a new poll by the Public Policy Institute of California.
56 percent of those polled said they would vote for Obama. 33 percent said they support McCain.
Officials with the institute said that was the widest lead Obama has yet enjoyed.
Voters still report high party loyalty, but Republican support for their ticket is slipping.
44 percent of them said they are satisfied with the candidates, down from 67 percent a month ago.
Voters overwhelmingly rated the economy the top issue and said they want to hear more about it from the presidential candidates.
Californians also have slightly more faith their Republican governor after he finally signed the latest budget in state history.
The poll found Governor Schwarzenegger's approval rating at 47 percent, up from 38 percent a month ago.
The state Legislature's rating is virtually unchanged, at 22 percent, as both sides get set to reopen that budget because of falling revenues.
The Poll was conducted from Oct. 12 - 19 by telephone with 2,004 California adult residents.
1,186 of the people polled were considered likely voters. There was a sampling error of plus or minus 2 percentage points for all adults; plus or minus 3 percentage points for likely voters.