The Seattle City Council is debating behind closed doors this week over whether to move forward with a pilot program that would bring municipal broadband to part of the city’s North Beacon Hill neighborhood.

The $5 million project would serve as an experiment, testing the possibility of building the same kind of network across the entire city — a much more ambitious undertaking that would likely cost between $480 million and $665 million, according to a study commissioned by the city in June.

The mayor’s office has spoken out against the larger fiber buildout, and said the pilot proposal is “not a wise” use of public funds. But council member Kshama Sawant, with the support of Nick Licata and Bruce Harrell, is still pushing for the $5 million line item to be included in Seattle’s budget. They’ll need about five votes to get it passed.

Council members will continue debating what makes it into the budget all week, and next week they’ll vote on a final version. If the broadband pilot doesn’t make the cut, it could be added as an amendment later in this budget process, or during supplemental budgets later in the year.

Municipal broadband has been a hotly debated issue across the U.S., as cities from Seattle to Savannah, Ga. have tried to figure out how to treat Internet service. Municipal broadband supporters say something so fundamental to economic success should be a considered public infrastructure like roads or electricity.

Meanwhile, large Internet providers — like Comcast and CenturyLink — and budget-conscious local leaders have pushed back, arguing it should be left to the public markets.

Sawant has been the loudest voice calling for municipal broadband in Seattle. She says building a government-owned fiber network would lower the cost of Internet service for everyone and bring next generation connection speeds to underserved parts of the city.

Meanwhile, Seattle Mayor Ed Murray’s office has said the kind of network Sawant is talking about is too expensive and risky for the city to build on its own. For it to be possible, Seattle CTO Michael Mattmiller says the city would need federal grants or some type of outside funding that it hasn’t secured yet.

Mattmiller and Ben Noble, director of the Budget Office, discouraged officials from supporting the $5 million pilot project in a letter sent to the council last week. They wrote that the experiment would likely be challenged in court and, even if it was built, probably wouldn’t offer many usable insights into the feasibility of a broader fiber buildout.

“For these reasons, and the high risk any ensuing citywide network poses to the City’s and the taxpayers’ finances, a pilot is not a wise allocation of existing resources at this time,” the letter reads.

But Upgrade Seattle, a grassroots movement pushing for municipal broadband, disagrees. Organizers Karen Toering and Sabrina Roach call the pilot program a “measured approach to trying” to make municipal broadband work.

They argue that the complete buildout would likely end up costing less than the $480 million the city anticipates, but it would still be possible even if it does cost that much. They pointed out the proposal is significantly smaller than the $930 million transportation levy voters just approved last week, and 65 percent of Seattleites say they want municipal broadband.

“We’re looking at the same [feasibility] report as the Mayor’s office, but seeing different things,” Toering said, adding that it feels like they’re closer than ever before to getting the city council support they need to move forward with the project.

These budget debates can be hard to predict. They happen outside of the public spotlight, but we should start to see how City Council is leaning when it votes publicly next week. In the meantime, Upgrade Seattle is encouraging supporters to contact council members as part of a letter writing campaign.

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