About 45 percent of the in-state donations to California gubernatorial candidate Jerry Brown came from individuals, businesses and groups located in Oakland, where he was mayor from 1999 to 2007.

All told, that's $8.4 million of the $18.8 million Brown reported raising from California donors in the first half of 2010. He also received about $700,000 in out-of-state donations.

"After eight years of office there, Brown has people he's connected to that would serve as natural donor base," said Jack Citrin, a professor of political science at UC Berkeley.

Citrin said though he was surprised so much money from Oakland flowed to Brown, it's doubtful that the percentage will be as high at the end of the election season.

"Brown has reserves from his previous campaigns and unions remain big funders for him, but he's got to be able to have people from around the state write checks for him," Citrin said.

Click here to read a special feature about Brown campaign donors.

Sacramento donors raised about half as much as those in Oakland, where Brown still lives.

L.A., San Francisco and San Diego rounded out the top five in terms of monetary support for the Democratic candidate. The five cities were also the only ones to have more than 100 listed donors, according to an analysis by Neon Tommy of state campaign finance records for Jan. 1 through June 30.

Oakland resident James Fristrom, who donated $2,500 to Brown's campaign, suggested Brown's success as mayor of Oakland makes him and most of his neighbors Brown supporters.

“He feels safe in Oakland, which he should," Fristrom said. "From what I understand he is very well liked.”

Another Bay Area resident and Brown campaign contributor, Rebekah Mikkelsen of Mountain View, said despite his Northern California ties, Brown’s lack of visibility is hurting him.

“On my way to Palo Alto, you pass an IKEA with a huge electronic billboard," she said. "Every five seconds or so, you see Meg Whitman in a field of poppies that says ‘Meg 2010’."

Republican Meg Whitman, Brown's opponent, received most of her checks from San Diego. However, L.A. donors provided the greatest amount of money.

Whitman solicited nearly $500,000 from donors who listed New York City addresses. Citrin said the figure makes sense because of California's role in the national economy and the lack of a residency requirement to make campaign contributions.

The analysis excluded donations the candidates made to their own campaigns. Also excluded were donations made to Brown's 2010 Attorney General Committee, which received only $13,550 during the first half of 2010.

Both graphics by Monica Nguyen.

Both graphics by Monica Nguyen

To read thoughts from Brown campaign donors that are not included in the special feature above, click here.

Staff reporter Andria Kowalchik and contributor Kendall Bullock contributed to this story.

Reach reporter Monica Nguyen here.

To reach reporter Paresh Dave, click here.

Find him on Twitter: @peard33.

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