Seattle councilmember Kshama Sawant wants a municipal broadband network in the Emerald City, and she’s calling on the city’s residents to join forces to make it happen.

Sawant, a former software engineer who was elected to the Seattle City Council as a socialist candidate in January 2014, penned a blog post today advocating a city-owned network that would make Internet a public utility.

“The purpose of a public internet utility is to provide high-speed, affordable and equitable internet coverage to all Seattle neighborhoods, residents, and businesses,” she wrote. “Municipal broadband can be a powerful lever against the digital divide that condemns people to the isolation and reduced economic opportunities experienced by many of our low-income, disabled, and people of color community members.”

Sawant’s post was published on the same day that the city released details of a 7-month study showing that building a municipal gigabit fiber network in Seattle would cost $480 million to $665 million. That would be too expensive and too risky for the city to pursue the project alone, according to the city’s technology and budget officials.

The study, by an outside consultant, suggested that the city should work with an external partner to develop and deploy the broadband network as part of a joint venture instead.

One reason the municipal broadband project is risky is the likelihood of price cuts by the incumbent providers. That would reduce the appeal of the city’s network and cut into the revenue needed to pay back debt required to finance the municipal system.

Sawant wrote that “we should expect Comcast and CenturyLink to go to every length to keep their unchallenged duopoly in Seattle.” She added, “Countering them will require a mass citywide movement, much like the one we needed to win $15/hour last year by successfully overcoming the financial and political clout of fast food and retail giants.”

GeekWire has contacted both Comcast and CenturyLink for comment on the consultant’s report and Sawant’s comments.

Sawant heads up the City Council’s Energy Committee, and last month, she invited leaders from Upgrade Seattle to an Energy Committee meeting to talk about why Seattle should take advantage of its dormant “dark fiber” network and treat Internet access as a utility, similar to how it handles electricity.

Today, she also encouraged residents to “get involved in this year’s process of appointing a new general manager for Seattle City Light and provide their input on whether a commitment to municipal broadband should be a selection criterion for the job.”

Sawant concluded, “It is up to us working people to build a strong enough grassroots movement for municipal broadband to force elected officials to put Seattle’s need for universal, affordable high speed connectivity over Comcast and CenturyLink’s insatiable drive for profits.”

[Editor’s Note: CenturyLink, Frontier Communications, and Wave Broadband are GeekWire annual sponsors; Comcast is a GeekWire advertiser.]