While Republicans are proudly supporting sharing economy startups to boost their support among young voters, Democrats appear to be doing the opposite. A leading senator and former mayor of San Francisco, Dianne Feinstein (D-Calif.), penned a rather aggressive op-ed against rental startups for the San Francisco Chronicle, “Don’t hand San Francisco over to Airbnb.”

San Francisco’s board of supervisors recently voted to legalize short-term rentals through Airbnb, allowing residents to rent out their home for less than 30 days. It limits rentals beyond 90 days, establishes a registry for hosts, and requires a $500,000 insurance policy.

The law couldn’t come quick enough. Despite being illegal, Airbnb rentals are quite popular in the city, leading one citizen activist group to start seeking out renters and snitching on them to authorities.

Naturally, Airbnb praised the law, but Feinstein is not pleased. “I know firsthand the merits of strong zoning laws. They protect residential areas so they can support families and be free of commercial activities that are not related to neighborhood needs,” she argues.

Feinstein believes that Airbnb would bring uninvited guests into these neighborhoods and lead homeowners to take limited housing stock off the market, as well as reducing valuable hotel tax revenue from the city.

Research by the Chronicle, however, seems to show that most renters are simply using Airbnb income to help pay the rent on their primary residences. About two-thirds of San Francisco listings have fewer than 10 reviews, meaning that they are only used occasionally. Additionally, about 84 percent of hosts only have a single listing, rather than hosts buying up many homes and putting multiple rooms on the market.

Feinstein also believes that the law does not collect enough taxes. “The tab for back taxes for Airbnb rentals alone is estimated at more than $25 million. … I believe there is a compromise solution, but it does not involve handing over the key to the city to Airbnb and other short-term residential rental companies.”

Feinstein’s unusually harsh op-ed is rare, both in terms of its local focus and its targeting of a specific company. But she has close ties to the very city at the heart of the sharing economy: She served as its mayor and maintains a residence there.

San Francisco is pretty liberal, as are most tech CEOs. But if Democrats continue to go after the tech industry, it may not stay that way for long.