Independent groups with money from oil companies, grocery workers and apartment owners have unleashed hundreds of thousands of dollars in recent days to take out several members of the California Legislature, breaking with political custom that generally protects incumbents from well-funded challenges from within their party.
In Silicon Valley, an outside committee backed by oil companies Chevron, Valero and others had spent $339,000 through Sunday to support Assemblywoman Nora Campos, D-San Jose, who is running against state Sen. Jim Beall, D-San Jose, in the 15th Senate District.
The same group, as well as another that gets money from the real estate industry and apartment owners, has spent several hundred thousand dollars to help former Assemblyman Raul Bocanegra or oppose the incumbent, Assemblywoman Patty Lopez, D-San Fernando, in Los Angeles County’s 39th Assembly District.
An outside spending committee funded by Rep. Devin Nunes, R-Tulare, reported $15,000 in spending on mailers to support Rudy Mendoza, the Republican opponent of Assemblyman Devon Mathis, R-Visalia, in the San Joaquin Valley’s 26th Assembly District.
And in the Inland Empire, a campaign committee funded by the grocery workers union has spent $75,000 to support Eloise Gomez Reyes, the Democrat running to unseat Assemblywoman Cheryl Brown, D-San Bernardino, in the 47th Assembly District.

It’s common for independent expenditure groups to get involved in races for open seats, such as the Davis-to-Vallejo 3rd Senate District, where independent expenditure committees have spent $860,000 to support Assemblyman Bill Dodd in the race to replace termed-out state Sen. Lois Wolk, D-Davis. But it is rare for outside groups to spend heavily to swap out incumbents for candidates of the same party.
“Clearly, interest groups are getting involved in these same-party primaries,” said Tony Quinn, a Republican political analyst. The state’s top-two primary system, approved by voters in 2010, has given those groups more of an opportunity to elect preferred candidates in districts dominated by voters of one party because candidates of the same party can advance to fall runoffs.
Different issues seem to be at play for the four incumbents, so far, whose rivals have received backing from outside groups. Oil companies, for instance, butted heads with Beall and other Senate Democrats last year over legislation that sought to reduce gasoline consumption.
In the Visalia-based 26th Assembly District, Mathis faces a rematch against Republican Mendoza. The congressional campaign of Nunes, for whom Mendoza once worked, has donated $50,000 to Republicans for Lower Taxes 2016, Supporting Rudy Mendoza for Assembly District 26.
“He thinks Rudy Mendoza would be a better member of the Assembly,” said Richard Temple, a consultant to the pro-Mendoza committee. Mendoza has criticized Mathis’ support for February legislation expanding a health plan tax, saying the bill is a tax increase, but others, including the influential Howard Jarvis Taxpayers Association, have said the measure was tax neutral.

Incumbents have faced strong intraparty challenges before. In 2012, then-Assembly members Mike Allen, D-Santa Rosa, and Betsy Butler, D-Los Angeles, lost their seats to fellow Democrats after campaigns in which outside groups spent heavily. But the previous year’s redrawing of political districts had shifted away much of Allen and Butler’s political bases.
Similarly, incumbents tainted by scandal sometimes face well-funded challengers from the same party. In 2008, state Sen. Carole Migden lost her re-election to then-Assemblyman Mark Leno, D-San Francisco, following a year in which Migden received probation for reckless driving and was fined for campaign finance violations. It was the first same-party ouster of an incumbent in a dozen years.

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