Harder said in an interview that he's been focusing his campaign locally, but the competitive nature of the race has spurred individual contributions from across the state.
"This is a focus-magnet district for everybody," Harder said. Other than the seats that are already blue, "it's the only winnable election we have in Northern California, so to the extent other folks want to help, that's great," he said.
As one of the richest areas in the country, Silicon Valley certainly has the economic means to spread the wealth. The median household income in its two districts is more than $120,000, or about double the median income in Harder's district, according to U.S. Census data.
There's likely a lot more tech money and support to come as November nears. Swing Left and Tech for Campaigns, two organizations that focus on progressive candidates, told CNBC that they've received a flood of interest from Silicon Valley. Jessica Alter, co-founder of Tech for Campaigns, said it has nearly 2,000 volunteers from California, and that about 60 percent of its overall volunteers are first-time activists.
But both organizations said they won't be mobilizing volunteers and money in California until after the primaries.
District 49 is one reason why. In campaigning for the seat that Issa has held since 2001, Levin is one of four Democrats competing against a field of seven Republicans and one independent, according to fundraising records.
Levin has significantly higher contributions from the tech space — led by Alphabet — than his competitors, but he's raised less overall than two of his Democratic challengers. Levin, who spent more than a decade as an environmental attorney, is focusing his campaign on clean energy, affordable health care and preventing gun violence.
"This election is either going to be a validation of what this president stands for or a repudiation of it," Levin said. "As Californians, we stand up for a clean environment, we stand for those who are most vulnerable and we stand for equality."