New England Confectionery Co. (NECCO), maker of the iconic Valentine's Day conversation hearts candy Sweethearts, celebrated its 170th anniversary last year. But unless a buyer is found by May 6, the company has notified the city of Revere, Mass., it may have to lay off 395 employees and potentially close its manufacturing plant, reports The Boston Globe.

According to The Globe, NECCO is the Boston suburb’s largest employer. Along with conversation Sweethearts, the company also produces Mary Janes, NECCO Wafers, Clark Bars and Candy Buttons.

The company has been in ongoing in negotiations with potential buyers to allow the plant to continue operating. But NECCO notified Revere and the state of Massachusetts that there is no assurance a sale will be finalized or that the business would be able to keep all of its existing employees.

NECCO CEO Michael McGee wrote in a letter to Revere officials, “We deeply regret and understand the uncertainty this action may cause our valued employees.” Last year, NECCO sold the 810,000-sq-ft building in Revere to Atlantic Management of Framingham, Mass., and VMD Cos. of North Andover, Mass.

Necco’s Sweethearts might be the company’s most iconic candies. According to Necco, approximately 2 billion individual boxes are sold in the six weeks surrounding Valentine’s Day.

Should Necco close, other candy companies, such as Brach's and Wonka, could move in with their own version of the classic conversation hearts for Valentine’s Day. Wonka SweeTarts Hearts are tangier, and the phrases are embossed. But Brach's Conversation Hearts are pretty similar to Necco's with stamped-on lettering.

Necco has yet to call it quits, however. In the letter, McGee told Revere's mayor he'd put out an SOS message to potential buyers that said: "Call Me."

Revere Mayor Brian Arrigo said it the city has been working with Atlantic Management to rezone the site for advanced manufacturing, robotics and e-commerce and, hopefully, NECCO’s continued production. "But if they do close their doors, we will still have a viable option for businesses suited to support Revere’s 21st century economy. And, of course, we will work with state and regional agencies to assist any displaced workers to find new employment opportunities.”