Standing in the drizzle outside of St. Luke’s Hospital, Hillary Ronen officially announced her candidacy for District 9 supervisor Thursday afternoon, pledging the construction of thousands of units of new affordable housing and attacking Mayor Ed Lee for ignoring community input.

“I will build 5,000 units of affordable housing in District 9 in 10 years,” she said, flanked by supervisors David Campos, John Avalos, and Eric Mar.

Ronen, who has worked as Campos’s chief of staff since 2010, outlined her plan to Mission Local a day before the announcement, saying she would build up empty lots and raise heights when feasible to accomplish her goal.

Funding, not space, will likely be the main obstacle, however, and Ronen’s commitment to fight for state and federal funds, as well as her position that corporations should contribute to solving the affordability crisis, presents an uphill climb for a city supervisor.

The district already won $50 million for affordable housing in November’s bond, and some 480 units have been planned for construction in the last eight years under Supervisor David Campos, Ronen pointed out. But that is only 10 percent of the pledge Ronen is making, and for her to live up to the campaign promise Ronen would need to build more than 600 affordable units every year of her tenure.

“For her to be talking about building housing is rich,” said political consultant David Latterman, who recently worked with Julie Christensen’s losing campaign in District 3 and helped David Chiu defeat Campos for State Assembly in 2014. Hammering Campos’s housing record was a key strategy in the 2014 campaign, he said, and Latterman predicts Ronen will have to juggle Campos’s endorsement against this legacy.

“She’s going to try to embrace ‘I am Campos’s chosen successor’ and slowly back away from his housing record,” he said.

Ronen says she will be “laser-focused” on her district and building these units, while Campos was “more of a supervisor for the entire city.”

“He worked on big initiatives that are going to make change for all San Franciscans,” Ronen said. “I am going to be a supervisor with a laser focus on District 9. I am going to build 5,000 units and that requires an attention to the district like never before.”

While neither side of the political aisle is against rapid construction of affordable housing, all acknowledged it would be a tremendous task.

“It’s a great idea, but it’s going to be very difficult,” said Tommi Avicolli Mecca, director of counseling at the Housing Rights Collective. The lack of funding from city hall is the major factor, and Ronen would be a reliable vote at the Board of Supervisors for pushing such construction, he said. “You gotta go for it.”

Ronen is running against three other candidates. Joshua Arce is the more moderate of the four, with ties to labor unions and friendly to the mayor, the latter a possible detriment in the Mission and Bernal Heights but perhaps a boon in the Portola, with its more moderate Asian voting bloc.

Sharing most of Ronen’s political positions is Edwin Lindo, vice-president of external affairs at the Latino Democratic Club, whose campaign lacks the resources and heavy backing of Ronen and Arce — though he does split Supervisor Mar’s endorsement with Ronen. Instead, Lindo has underscored his status as a Mission native and emphasized an impoverished background in the neighborhood.

Though Ronen has worked in the district for 13 years and lived in the Mission previously, she moved to the Portola just four months ago from Sunnyside.

A fourth candidate is Iswari España who is running on a platform to “stop playing politics and focus on accountability of services for residents of District 9.”

A Guatemalan immigrant who settled in the Mission in 1987, España is a little-known candidate who characterized his opponents as “well-established attorneys with the same lines.” He has a background in non-profit and government work and is currently at Success Center San Francisco, a non-profit that educates juvenile youth.

Despite the full field, Ronen’s kick-off has been the most momentous so far. More than 100 people braved the downcast weather to hear Ronen’s speech outside St. Luke’s Hospital, a venue chosen for its symbolic value as a victory of Ronen’s against Mayor Lee’s plan to shut it down in favor of a Cathedral Hill hospital.

“Unfortunately, this is what we have come to expect from this administration,” said Ronen, lambasting Lee for “shortsighted thinking” and “shutting out community voices” while simultaneously garnering praise from a crowd that included local nurses.

An obligatory moment of political awkwardness accompanied Ronen’s speech when she asked how many in the crowd had been born at St. Luke’s and just one raised his hand. Ronen quickly revised her question to how many had been treated at the hospital — and dozens shot up.

Ronen’s supporters unequivocally viewed their candidate as a competent, connected choice.

“I think she’s a political superstar,” said Karen Gee, a Portola resident since 1983. “She’s young, she has work experience, and she’s a mother so she has family values.”

Juana Flores, a Mission resident who met Ronen when she was an attorney at La Raza Centro Legal, said Ronen “always supported the immigrant community and the female community” and praised her work with laborers and domestic violence victims.

“I know she has a lot of community support,” she said.

The District 9 race is key for future city politics. Not only will its outcome affect the Board of Supervisors in an election when the progressive majority is in question, but with the Mission as ground-zero in San Francisco’s gentrification wars, a progressive loss there would be both an embarrassment for and hindrance to progressive housing plans city-wide.

All of which will bring street canvassing and donor money. Whether or not infighting marks the discourse between the two progressives, Lindo and Ronen, or there is an attempt to tackle the more moderate Arce — and what role España will play in shaping the debate — the District 9 race is heating up to be one of the most important in the 2016 elections.

“From an ‘I like watching San Francisco politics’ point-of-view, this is going to be a fun one to watch,” said Latterman. “Sit back with your thing of popcorn and just watch the show.”