Former eBay CEO Meg Whitman (R) won California's GOP gubernatorial nomination Tuesday.

With 1,224 of 22,896 precincts reporting, Whitman was declared the winner by the Associated Press. She had 64 percent of the vote to 26 percent for state Insurance Commissioner Steve Poizner, according to unofficial results.

The combined spending between the two candidates topped $100 million, by most estimates. Whitman reportedly spent close to $70 million from her own fortune, while Poizner cut himself checks for close to $24 million.

"It's not only the most expensive statewide primary, it exceeds statewide races in their entirety," said Lynn Vavreck, director of the University of California Los Angeles's Center for the Study of Campaigns.

This will be the most expensive governor's race in California history, she added.

California Attorney General Jerry Brown won the Democratic nomination with 83 percent of the vote. He had more than $20 million banked ahead of Tuesday's primary.

Whitman won endorsements from several influential conservatives, including former Vice President Dick Cheney, during the primary. That courtship of the conservative right is what the Democratic Governors Association zeroed in on Tuesday night.

"Whitman needed to pass the Tea Party purity test to win her primary, and she's undercut her appeal to moderates and Latinos," Nathan Daschle, the DGA's executive director, said in a statement. "Her failed business efforts and her ties to Goldman Sachs will only add to the ghosts she'll have to confront between now and November."

— This post was updated at 12:05 a.m.