Justin Sullivan | Getty Images
Sen. Ted Cruz (R-TX) speaks at the NRA-ILA Leadership Forum during the NRA Annual Meeting & Exhibits on May 4, 2018 in Dallas, Texas.
Miller said that O’Rourke’s message is well-suited to the coastal millennials populating tech companies. He’s active on social media and his campaign spent more than $5 million on Facebook ads between May and Oct. 20, the most of any U.S. advertiser.
“I think that both sides will see this as a win for them,” Miller said, referring to O’Rourke’s tech contributions.
Neither campaign responded to requests for comment.
Cruz has gotten plenty of support from other industries. Employees at financial institutions, like Berkshire Hathaway, Goldman Sachs and Woodforest Financial Group are some of his top contributors. He’s also received funding from workers at industrial companies like Lockheed Martin and energy companies such as PBF Energy and Quantum Energy Partners.
O’Rourke isn’t the only Democrat in a tight race to receive backing from tech employees. Sen. Claire McCaskill, D-Mo., who is in a heated bid to keep her seat against Republican Josh Hawley, has been the top recipient for Facebook money and is third among Google employees. And Sen. Heidi Heitkamp, D-N.D., has been a popular target for tech funds as she tries to stave off Republican challenger Kevin Cramer.
As of mid-September, roughly 40 percent of the more than half a billion dollars in direct contributions raised by Senate candidates had flowed into just 10 competitive races, including Texas, according to a CNBC analysis of Center for Responsive Politics Data.
But O’Rourke’s campaign is unique in the tech industry and beyond. He’s raised more money in three months than any previous Senate candidate in history.
“In this era of low-dollar fundraising, money is going to be directed to the candidates that can garner excitement among their relative bases,” Miller said. “That’s true of both sides.”
— CNBC’s Ari Levy contributed to this report.
WATCH: Sen. Cruz discusses Trump’s position on Obamacare