With about 30,000 absentee ballots left to count, Ro Khanna conceded the 17th District race to Congressman Mike Honda, who declared victory Friday morning, saying he had an "insurmountable lead" over his opponent.
"I just called Congressman Honda to congratulate him on his victory after a hard-fought campaign,” said Khanna, speaking Friday night before a crowd of supporters at his Fremont headquarters.
Earlier in the day, Honda, 73, promised he would stick around for a long time: "I'm not going anywhere. I'm going to live until 103. There's no reason to retire."
He said his tough election against fellow Democratic challenger Ro Khanna shows that "you cannot buy grassroots. Democracy is not for sale." He said he was outspent 2 to 1.
Honda has held his seat, which stretches from San Jose north through Newark, since 2001. If reelected, he will begin his eighth term in January.
As of Friday morning, Honda was ahead with 52 percent of the vote -- slightly more than 4,000 votes or 4.4 percentage points.
As of Friday, there were still about 30,000 absentee ballots left in Santa Clara and Alameda counties. Election workers were expected to count throughout the weekend.
The Associated Press called the race for Honda shortly before 6 p.m. Friday night.
Honda was endorsed by political heavyweights such as President Barack Obama, Gov. Jerry Brown, state Attorney General Kamala Harris and Rep. Nancy Pelosi, D-San Francisco.
Khanna, a 38-year-old lawyer, ran in part on his background in technology and as a former commerce official for President Barack Obama's administration in a district that includes some of Silicon Valley's major tech businesses.
Khanna's endorsers featured an impressive array of major Silicon Valley executives, including Facebook chief operating executive Sheryl Sandberg, Google head Eric Schmidt, Yahoo! CEO Marissa Mayer and other business leaders from tech firms like Microsoft, Oracle and Yelp.
Another big South Bay race has still not been officially called: that of San Jose mayor. Sam Liccardo on Friday was leading Dave Cortese 51.5 percent to 48.5 percent, with about 40,000 ballots left to count in the city of San Jose. Gerston said while it's likely that Liccardo will win, it was premature of him on Wednesday to declare a hard victory.
NBC Bay Area's Nannette Miranda and Kinsey Kiriakos contributed to this report.