Early voting starts today, and of all the housing measures on the November ballot, perhaps none is more contentious than Prop. I, the Mission moratorium.

The measure, which requires a simple majority to pass, would pause all market-rate housing for 18 months and prevent the conversion of light industrial space, known as production, distribution, and retail (PDR), in the Mission District. Proponents say it will give the city and non-profits time to formulate a plan for developing affordable housing in the Mission, while opponents claim any pause in construction is counterproductive if the goal is to build more housing.

“We’re in a shortage, so we need more houses not less,” said Sonja Trauss from the San Francisco Bay Area Renters Federation, a new group founded in May 2014 that promotes a supply-side approach to the city’s housing shortage. “It’s not really a complicated position. We really need a massive building program.”

Gabriel Medina, the policy manager at the Mission Economic Development Agency (MEDA) and a leader in the “Yes on I” campaign, doesn’t buy that argument.

“If you keep building more housing and offices for [people], you’re increasing the demand [for housing]. The more you continue to build the more you’re going to continue to displace people, as we’ve seen during this building boom in the Mission,” he said. “Construction of market-rate [housing] attracts more people who have high incomes, and it’s a self-perpetuating cycle that you can’t outbuild.”

The “Yes on I” campaign argues that building market-rate housing actually increases demand instead of decreasing it by attracting even more people to San Francisco. Such housing also raises rental and commercial prices for existing residents, they say, which is why a pause on development is needed to formulate a plan for affordable housing in the Mission.

“The most important thing with Prop. I is leverage and negotiating with the city,” Medina said. Prop. I requires that San Francisco create a plan for housing in the Mission District by early 2017 to make at least 50 percent of new housing in the neighborhood go to low and moderate-income residents. The latter includes those making from $36,000 to $86,000 for a single-person household.

While San Francisco has built a fair amount of market-rate housing in recent years, it has only finished about 14 percent of its needed low and moderate-income housing, according to the Planning Department. To those in favor of a moratorium, that performance means a plan is needed.  

“The fact that there’s no plan for affordable housing in the Mission is why [Prop.] I is on the ballot,” said Jon Golinger, an environmental attorney and a co-chair of the new political organization Vision SF. “[Prop.] I is on the ballot to demand a plan.”

Ted Egan, the city’s chief economist, however, published a report last month that said a moratorium would have no long-term effect on housing in the Mission.

“A temporary moratorium would lead to slightly higher housing prices across the city, have no appreciable effect on no-fault eviction pressures and have a limited impact on the city’s ability to produce affordable housing during the moratorium period,” the report read.

Medina, for one, does not share that analysis.

Under Egan’s logic, it’s ‘Build, build, build and don’t look at what that actually looks like on paper or in the real world,'” he said. “For us, we’re looking at the people and the building environment.”

In the fight between non-profits and developers, one side is vastly outspent. The “Yes on I” campaign has raised some $80,000 for the election, while its opponents have brought in some $500,000, a $200,000 chunk of which is coming from developers for the controversial 16th and Mission housing project.

The ballot measure is similar to a 45-day moratorium Supervisor David Campos brought to the Board of Supervisors in June, which was voted 7-4 but required nine votes to pass. Its failure led MEDA and other groups to reconceive of the moratorium as a ballot initiative, gathering the needed 15,000 signatures in three weeks in time for November’s election.