In January, Mayor Ed Lee stood against the backdrop of a construction site overlooking the bay during his State of the City address and called for 30,000 new or rehabilitated homes to be built in San Francisco by 2020.

Since then, a measure has qualified for the June ballot that members of Lee's administration say could threaten the construction of up to 3,690 planned housing units. Yet the mayor, who otherwise has appeared eager to tackle the city's housing crisis during the current tech boom, has so far refused to take a public stance on a proposal that could put a sizable dent in his stated goal.

The reason, according to political analysts, is simple: politics.

Proposition B, designed to limit waterfront development, is expected to win easily, analysts say, so Lee would have little to gain if he opposed it. But avoiding a major policy issue with an eye to the polls and his re-election undercuts the trademark narrative of Lee as a hard-working everyman above the political fray, said Jim Ross, a political consultant experienced with waterfront development, including the ballot measure to approve what is now AT&T Park.

"The antipolitician. I think, in a lot of ways, that's what makes Ed Lee refreshing and popular in San Francisco," he said. A thoughtful stance, even in a losing effort, likely won't hurt Lee's re-election chances, Ross said.

The idea of giving voters a direct say in the most contested aspect of waterfront development - height - is also popular, according to polls, particularly as the gap between San Francisco's wealthy and poor residents grows faster than in any other U.S. city.

Prop. B would require voter approval for any new building on Port of San Francisco property to exceed current height limits, which generally range from 40 to 105 feet.

Even some Prop. B critics concede it is expected to win easily.

'Why yes I would'

"Would you like free ice cream San Francisco? 'Why yes I would,' " is how one political consultant summed up Prop. B's voter appeal. "Why stand up against something where 60 to 70 percent are going to vote with the other side?"

Lee, who is friendly to business, faces re-election in November 2015, and some analysts say he has little to gain from being drawn into a losing political street fight with more liberal adversaries.

Opponents of Prop. B, though, say it threatens thousands of planned housing units - mostly rentals - and revenue sources for the port, which has at least $1.6 billion in infrastructure needs over the next 10 years.

The measure would directly impact three major projects already in the works: developer Forest City's plan to remake the industrial Pier 70 area; the San Francisco Giants' plan to build an urban village with plazas and towers on their main parking lot; and the Golden State Warriors' plan for an arena complex at Piers 30-32 - a proposal Lee once called "my legacy project."

That doesn't necessarily mean the projects won't get built, but they will have to change substantially or take on the added cost and uncertainty of going to voters if Prop. B passes.

No public position

Lee, as he has for several months, recently declined to take a public position on Prop. B, saying, "I think I'm content to let the voters decide that.

"Right now, I think there's a lot of things I have to concentrate on," Lee said. "There are a lot of housing developments that we are pushing that don't exceed height limits that are within the zone. I've got to concentrate on all the economics of that."

Lee also downplayed Prop. B's potential to undercut his goal of 30,000 new homes, saying, "on housing it's a little more indirect on how the impact will be."

However, in February an analysis by the port, which the mayor oversees and appoints all of its commissioners, found that Prop. B could cause 1,990 to 3,690 new housing units to be "delayed, reduced or abandoned." The report also found Prop. B could lead to almost $8.5 billion in lost revenue to the port over the long term and $124 million in affordable housing fees "delayed, reduced or forgone."

City's 'biggest issue'

"I think it's remarkable that the mayor is staying out of this fight," said Ross. "All fights in San Francisco come back to real estate. ... It's the biggest issue in the city."

Lee is certainly not the only politician shying away from a public stance on Prop. B, which was put on the ballot by many of the same limited-growth, politically progressive activists that defeated the 8 Washington condominium project near the Ferry Building in last November's election.

Board of Supervisors President David Chiu, one of 8 Washington's main opponents, says he is still deciding whether to support or remain neutral on the more expansive Prop. B.

Supervisor Scott Wiener, rarely one to shy from controversial topics, including a proposed soda tax and a public nudity ban, is parsing his response to Prop. B. Wiener last month voted to have the local Democratic Party oppose Prop. B but says that is separate from his personal position - he says he is neither endorsing nor opposing the measure.

'Future of San Francisco'

"This is much bigger than just a few condo developments. It's really to accommodate the future of San Francisco housing and employment," said David Latterman, a political science researcher at the University of San Francisco and consultant working on Chiu's state Assembly campaign. "It isn't just the mayor. It isn't just his administration. It's everybody. Everybody who cares about careful waterfront development needs to be more aggressive in defending that position."

Particular responsibility, though, falls on the mayor of this 47-square-mile city surrounded by water on three sides, Ross said.

"If you're mayor, you're going to have a big fight on real estate and land issues," he said. "You've got to figure out a way to lead the city."

The San Francisco Association of Realtors, which opposes Prop. B, listed Lee among the opponents of the measure in a recent poll. Lee was presented that way to test voters' response to "possible coalitions," said Jay Cheng, the association's deputy director for government affairs. He declined to provide the results, including whether Lee's inclusion swayed respondents to oppose it.

Lee and his advisers may be wary of associating the mayor, whose image was central in the barrage of pro-8 Washington TV ads, with another losing waterfront development campaign.

Welcome mayor's support

"Actually, we would welcome the mayor's support," said Jim Stearns, a consultant for the yes on B side. "We know he supports a vote on the Warriors' arena, and we think he should apply the same standard to the Giants and Forest City."

Lee is a "smart and agile politician who has a smart team around him who are going to ensure his political survival," said one political consultant who requested anonymity to speak candidly because of ties to the Prop. B fight. "They are saying, 'Run away from Prop. B and any development discussions as fast as you can.' "

That may not be the best advice, Ross and others said.

"My advice would be to be true to yourself," Ross said. "That's who you are. I feel like trying to stay neutral and stay out of these big ballot measures, it feels like a politician. A politician tries to have it both ways."