For years, Representative Ro Khanna was Silicon Valley’s favored son in Washington, the tech-backed insurgent who toppled a popular Democratic incumbent and became a national voice on innovation and inequality. Now, many of the same forces that helped build his career are lining up behind a challenger determined to end it.

Ethan Agarwal, a 40-year-old entrepreneur with deep roots in the Valley’s elite, has launched a campaign for California’s 17th congressional district, home to Apple, Intel and some of the world’s most valuable companies. A Wharton graduate and former McKinsey consultant, Agarwal founded and sold the audio fitness startup Aaptiv and later co-founded financial services firm Coterie, backed by powerhouse venture firm Andreessen Horowitz.

His candidacy crystallizes a growing rift between the tech industry’s billionaire class and Khanna, a 49-year-old Democrat once embraced as their emissary in Washington. The break came as Khanna moved left on economic policy, most notably by endorsing a California wealth tax and co-sponsoring federal legislation with Senator Bernie Sanders to impose a 5 percent annual levy on fortunes over $1 billion.

That proposal, pitched as a way to raise trillions in new revenue, infuriated many of the Valley’s wealthiest founders and investors, who saw it as a direct assault on the fortunes they built. Agarwal says Khanna’s support for the wealth tax was “the straw that broke the camel’s back” and cast himself as the candidate who will defend innovation while tightening rules on how the ultra-rich actually use their money.

Agarwal is hardly a populist outsider. His early backers include prominent tech figures such as Y Combinator chief executive Garry Tan and DoorDash co-founder Stanley Tang, with more expected to follow. That support is likely to fuel accusations that he is a vehicle for billionaire grievances, a charge once leveled at Khanna himself when he first ran with the blessing of Marc Andreessen, Sheryl Sandberg and Eric Schmidt.

The emerging contest is as much a referendum on power as on policy. Khanna has built a national profile, floated as a future presidential contender while pushing aggressive tax and regulatory ideas. Agarwal is betting that voters in the country’s wealthiest district are ready to punish a congressman who turned on the class that helped elect him — and to replace him with a new face molded, funded and now unleashed by Silicon Valley itself.