"Howard Berman understands how to reach across the aisle to get things done on behalf of our nation," Graham said in a statement released by Berman's campaign. "He works hard every day to advance America's agenda and has been instrumental in passing laws to prevent the spread of nuclear weapons, stop arms sales to nations that support terrorism, and keep our country safe. We need his effectiveness and bipartisan leadership in Congress."

The longtime congressman also has the backing of most of the state's big-name Democratic politicians, including California Gov. Jerry Brown and Sens. Dianne FeinsteinDianne Emiel FeinsteinTrump’s CIA pick facing brutal confirmation fight This week: Senate barrels toward showdown over Pompeo Sunday Shows Preview: Emmanuel Macron talks ahead of state dinner MORE (Calif.) and Barbara BoxerBarbara Levy BoxerThe ‘bang for the buck’ theory fueling Trump’s infrastructure plan Kamala Harris endorses Gavin Newsom for California governor Dems face hard choice for State of the Union response MORE (Calif.).

Berman and Sherman are facing off in a district that mostly comprises Sherman's current territory. Sherman, who has run to Berman's left, has a cash advantage heading into the general election and led in the first round of voting. Berman's promotion of these Republican endorsements shows he sees the need to win most Republicans and independents in the heavily Democratic district to pull off a victory.