Philadelphia is on the brink of becoming the first U.S. city to bar employers from asking potential hires for their salary history, a step aimed at narrowing the pay gap between men and women.

The wage-history bill unanimously passed by the city council now sits on the desk of Democratic Mayor Jim Kenney who said Thursday he expects to sign it as soon as Monday.

Key players in the business community, including Comcast Corp., are pushing for a veto, claiming the ordinance, passed in December, wouldn’t work as intended and saying it would violate employers’ free speech rights.

But Mr. Kenney said the city doesn’t think the bill’s critics have valid legal arguments.

“We may get sued, we may not,” he told reporters Thursday. “But council passed this measure by a unanimous vote, and I see no reason why I shouldn’t sign it.”

Rob Wonderling, chief executive of the Chamber of Commerce for Greater Philadelphia, said the bill is the council’s latest antibusiness move, after passing mandatory paid sick leave and living-wage mandates in recent years. He said these measures create a pattern sending “a very negative signal that there is a significant hassle factor if you want to set up a business or conduct business in the city of Philadelphia.”

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