PORTLAND – Vendors at the Portland Public Market have organized in an effort to find a way to keep the market open.

The Libra Foundation, the charitable trust established by the late philanthropist Elizabeth Noyce, is listing seven properties, including the Portland Public Market, for sale in downtown Portland.

A group of vendors has now started a petition drive that asks Libra to reconsider its plans. The group also plans to launch a Web site in the next few days.

Vendors met Thursday to discuss their options. Afterward, organizers said they hope Libra will explore alternatives, such as selling the market separately to a buyer who wants to continue operating it.

“The market isn’t a real estate investment,” said Ted Spitzer, who with his wife owns Maine’s Pantry. “It’s not an office building. It needs a new vision and a new response.”

A Libra Foundation executive said vendors don’t seem to recognize that their rents fail to cover even half the cost of operating the 37,000-square-foot structure. Many vendors are profitable because Libra for years has subsidized their rents, said Jere Michelson, the foundation’s vice president and chief financial officer.

Michelson said the vendors’ petition would be forwarded to the foundation’s trustees.

“I don’t know if it will change anything, but it’s something for the trustees to discuss,” he said.