Democratic Congressman Ami Bera won his third term to represent a Sacramento-area district that national Republican leaders had targeted.
Bera faced a tough challenge from Republican Scott Jones, the Sacramento County sheriff who raised his profile by criticizing President Barack Obama's immigration policies.
Election results updated Friday showed Bera widening his lead to about 6,000 votes, or 2.4 percentage points, in California's 7th district.
Both candidates were bruised during the campaign.
Bera's father was sentenced to a year in prison in August for illegally funneling nearly $270,000 to his son's campaigns. Ami Bera wasn't charged and denied knowledge of his father's activities.
Jones withdrew his endorsement of Donald Trump after release of a tape of the presidential candidate bragging about his advances on women.