As Garry Tan, the Y Combinator CEO, has deepened his ambitions to become a political force, the task of turning his agenda into reality has often fallen on the shoulders of one guy: Forrest Liu, his political director. The work keeps Liu, 32, plenty busy—and occasionally requires him to put his body on the line as he drums up money and support for Tan’s platform.

When Liu went to a party in Healdsburg hosted by the CEO of a big fintech company recently, he left with a sprained ankle: It turned out his sandals were the wrong choice for the outing at the sprawling estate. A few weeks later, Liu was at a home near Taos, N.M., to meet with a billionaire, a former California resident who fled there to avoid the Golden State’s proposed wealth tax, which Tan strongly opposes. The estate sat at 7,000 feet—an invitation for altitude sickness for some. Lucky for Liu, the billionaire’s home had a special supply of supplemental oxygen available.

Liu and Tan channel the finances for their efforts through Garry’s List, a dark-money nonprofit that launched in February as well as a related political action committee, so they don’t have to disclose all of the money Liu brings in from his work with the wealthy and powerful. Liu said he is “constantly raising” money. Garry’s List has also hosted events with people like Gov. Gavin Newsom, and this month it plans to do one with the heavy favorite to replace him, Xavier Becerra. In June, the PAC spent $50,000 combating a San Francisco proposal that would have taxed certain highly paid CEOs. The measure failed.