San Francisco is the third city to tell Chick-fil-A: Keep out

First Boston. Then Chicago.

The next city to tell Chick-fil-A to keep out? San Francisco.

Edwin M. Lee, mayor of the progressive city, tweeted Thursday night: "Very disappointed #ChickFilA doesn't share San Francisco's values & strong commitment to equality for everyone."

He also added a warning to his subsequent tweet: "Closest #ChickFilA to San Francisco is 40 miles away & I strongly recommend that they not try to come any closer."

Until Thursday, San Francisco had stayed mum on the debate, which began when Chick-fil-A's president, Dan Cathy, went on the record as saying his Atlanta-based chicken chain operated on biblical values and opposed same-sex marriage.

He told an interviewer last week that the fast-food giant was “guilty as charged” of supporting “the biblical definition of the family unit,”

Since his comments, the reaction has been intense. Boston Mayor Thomas Menino told the Boston Herald that he no longer wanted Chick-fil-A in his city. Muppets creator Jim Henson Co. backed out of a partnership with the chain to make kids-meal toys.

Later, Chicago Mayor Rahm Emanuel issued a statement saying the company did not share "Chicago's values."

On Thursday, at a newly opened Chick-fil-A restaurant in Laguna Hills, customers were met by a group of protesters who urged them to buy fast food elsewhere.

Conservatives have been rallied by former presidential candidate Mike Huckabee, who has urged supporters to swarm into Chick-fil-A restaurants on Aug. 1. Conservative commentator Michelle Malkin blogged that Menino’s “beef with the beloved chicken sandwich supplier is as full of holes as Chick-fil-A’s trademark waffle fries.”

“When an elected public official wields the club of government against a Christian business in the name of 'tolerance,' it’s not harmless kid stuff,” Malkin wrote. “It’s chilling.”

Last week, Chick-fil-A issued a statement saying it would “leave the policy debate over same-sex marriage to the government and political arena." The company added that it has always aimed to “treat every person with honor, dignity and respect -- regardless of their belief, race, creed, sexual orientation or gender.”

No reaction yet from Los Angeles Mayor Antonio Villaraigosa, who supports same-sex marriage and is mayor to a city with a sizable LGBT population.