In the 49th District that straddles San Diego and Orange counties, Republican Darrell Issa, the wealthiest member of Congress, faced the stiffest challenge of his career against political neophyte Doug Applegate.
The eight-term congressman led by 2 percentage points, or about 4,000 votes of some 183,000 counted.
Applegate, an attorney and retired Marine colonel, was seeking elected office for the first time in a district with many military veterans like him. His campaign manager, Robert Dempsey, said he was "cautiously optimistic" about the results.
"We are slightly down but there are a lot of ballots to count," Dempsey said. "It's going to take a couple days before we even know how many people voted in the election. The process will work itself out."
Issa said he was confident his lead would hold. "The voters of the 49th District have spoken, and I am grateful for their support in our winning campaign," he said.
Applegate targeted Issa for his early and enthusiastic embrace of Trump and his role as President Barack Obama's chief inquisitor as chairman of the powerful House Oversight and Government Reform Committee from 2011 to 2015.
