This would be Brown's third term as California governor. He left the governorship 28 years ago.
Gov. Arnold Schwarzenegger released a statement Tuesday night congratulating Jerry Brown.
"Congratulations to Attorney General Jerry Brown on his hard-fought campaign and his victory tonight. Jerry has demonstrated his commitment to the people of California throughout a lifetime of public service as Governor, Mayor of Oakland and Attorney General, and I pledge to work with his incoming administration to provide the most efficient and smooth transition of power possible for the people of California."
Whitman Campaign Chairman and former California Governor Pete Wilson made a statement Tuesday at 10 p.m. declaring it was too early to call the race. "Be patient. It's going to be a longer night than I expected," Wilson told the Whitman crowd gathered in Universal City, Los Angeles. Later Tuesday night, Meg Whitman gave a concession speech, saying she called Brown to wish him well.
The results from an exclusive Eyewitness News SurveyUSA poll Monday showed Republican Meg Whitman with 37 percent of the vote, which is her lowest number in the past four months. Jerry Brown has 48 percent of the respondents, which is his highest number in the last four months. Six percent expected to vote for other candidates, and 9 percent were undecided.
Democrats had a 13-point voter registration lead in California.
A light overall turnout Tuesday would have favored Whitman.
"It's how interested the voters are and how turned off they are, and what's the balance," said Brown Tuesday. "And I would hope that we have a reasonable turnout."
"I'm going to win this, and it has been a privilege to run for governor," said Whitman Tuesday. "This is one incredible state with passionate, compassionate, generous and entrepreneurial people, and California can be great again."
"I think the signs look favorable, but we'll know when the polls close," said Brown. "Also, I have to add that I think it's going to be very tough over the next year or two. All signs point to some very hard decisions."
Whitman laid out an agenda to create jobs in California and save the state money by cutting thousands of state workers.
Brown has said he'll call lawmakers together and get their ideas.
Brown could not match Whitman's war chest, but independent groups stepped up in recent weeks to get the vote out, spending at least $25 million.
Labor unions, typically consistent in voting for the Democratic Party, put together a last-minute voter-turnout effort to counter a potential national Republican wave.
"What we've found is our members don't accept that we need a Wall Street CEO doing to the state of California what Arnold Schwarzenegger's done. The truth is she's just a mimic of Schwarzenegger," said Bill Camp, executive secretary of the Sacramento Central Labor Council in California, AFL-CIO.
At events on Monday, both candidates spoke with optimism about the future. Whitman visited a GOP field office in Woodland Hills and then met with supporters in Temecula.
"There's only one poll that matters and that's tomorrow's," Whitman said. "I know you know our polls still look really good. Our polls look great, so you know what? We're going to battle it out till the end. I feel great about where we are."
Brown attended the Get Out the Vote rally in downtown Los Angeles before returning to his hometown of Oakland.
Brown and Whitman have until 8 p.m. Tuesday when the polls close to finish convincing their voters.
Schwarzenegger voted Tuesday morning in West L.A., but he told reporters he wouldn't reveal until nighttime whether he chose Brown or Whitman.
The Associated Press contributed to this story.