Somewhere out there there's a number that will tell New York City when it's time to impose mandatory sick leave on businesses without crippling the economy, according to Council Speaker Christine Quinn. But, she told a Thursday night debate focusing on issues affecting low-income New Yorkers, she can't say what it is yet.

“There are a number of triggers you could look at: unemployment rates, closure rates, growth rates. We're trying to figure out all of those in different ways,” she told the crowd at First Corinthian Baptist Church in Harlem. As moderator Brian Lehrer noted, Quinn has said she opposes imposing sick leave now because of weaknesses in the economy.

Comptroller John Liu was quick to jump in. “There's no research that paid sick leave is detrimental to the economy,” he said to a roar from the crowd. Public Advocate Bill de Blasio, who in his opening remarks prodded Quinn to allow a vote on the sick-leave bill, also countered the speaker. “It is precisely in an economic crisis when people are hurting that we need paid sick leave,” he said. “With all due respect to Speaker Quinn, her answer to me is not believable.”

Along with Quinn, Liu and de Blasio, former Comptroller and Bill Thompson former Brooklyn Councilman Sal Albanese rounded out the Democrats on stage at the debate, sponsored by the Community Service Society (City Limits' parent company), 32BJ-SEIU, the Center for Popular Democracy, UnitedNY.com and City Limits.

(CSS earlier today released results from its annual survey of the "unheard third" of low-income New Yorkers. Read it here.)

Albanese referenced his sponsorship of the city's first living-wage bill in 1996. Thompson praised Mayor Bloomberg for restoring jobs lost in the recession and bringing in more high-tech industries, but said the benefits were not distributed evenly. “Opportunity for who? We're creating jobs for people not in our city.”

They were joined by Publisher Tom Allon, who has the Liberal party ballot slot, and former Bronx Borough President and Obama administration official Adolfo Carrion, who is the Independence Party nominee. Both are also seeking the GOP nomination.

Allon said he supported sick leave as long as the city also provides tax incentives to spur small businesses to offer wellness services to their workers, and criticized Bloomberg for policies that hurt small businesses. Carrion said the city ought to set a goal of attracting 70 million tourists. He added, “We need to move from just being a FIRE [finance, insurance and real estate] economy to being a FREIT [finance, real estate and technology] economy.

(Lehrer will air excerpts of the debate on his WNYC [93.9FM, 820AM] show in the 10 a.m. hour on Friday, March 1.)