PORTLAND – A federal judge in Maine has scheduled a July 10 meeting with class-action lawyers before deciding which of two groups will lead a lawsuit arising from last winter’s data breach at Hannaford Bros.

The case against the Scarborough-based supermarket giant began as more than 20 individual complaints filed in four states but has been consolidated in U.S. District Court in Portland before Judge D. Brock Hornby.

Competing to lead the case are a group of three firms based in Chicago, Miami and Philadelphia and a group composed of two Portland firms and one in Boston.

The class-action suit will seek compensation for people who lost money or suffered stress or inconvenience after Hannaford announced in March that 4.2 million credit and debit card numbers were exposed to computer hackers.