BOSTON — A cash-strapped Massachusetts museum urged a judge on the state’s highest court Tuesday to quickly sign off on a contentious plan to sell dozens of pieces of art, including works by Norman Rockwell.

An attorney for the Berkshire Museum told Justice David Lowy that it is nearing an April deadline to sell some of the works this spring — otherwise it will have to wait until the fall. The museum is in dire financial straits and losing money with each delay, attorney William Lee said.

“This is a situation where a museum that serves an enormous community purpose — that provides a window on the world to a group of folks who otherwise might not have it — is in dire circumstances and looking for a way to fulfill its mission,” Lee said.

The museum and Massachusetts’ attorney general are asking Lowy to approve an agreement they reached last month to allow the museum to sell up to 40 pieces of artwork.

Under the agreement, an unnamed U.S. museum would buy Rockwell’s “Shuffleton’s Barbershop” and loan the work to the Norman Rockwell Museum in Stockbridge for a period of time before lending it to other museums in the state.

The museum says it will sell the rest of the artwork until it reaches $55 million in proceeds. The museum says it may not have to sell all 39 other pieces, which include Rockwell’s “Shaftsbury Blacksmith Shop” and works by Alexander Calder, Albert Bierstadt and George Henry Durrie.

The judge didn’t immediately rule on the matter on Tuesday.

Rockwell’s sons, who went to court in October to halt the sale, dropped their challenge last month after the museum and attorney general announced that their agreement would keep “Shuffleton’s Barbershop” in public view.

The museum says the sale is the only option it has to keep its doors open. The museum has been running an operating deficit that in the past 10 years has averaged more than $1 million annually, and will close within eight years without an infusion of cash, it says.

An attorney for a group of museum members fighting the sale said Rockwell specifically chose the Berkshire Museum for his pieces because he wanted local residents to enjoy them. While the agreement ensures “Shuffleton’s Barbershop” can be viewed by the public, the other works may never be seen again, he said.

“Make no mistake, the art market is watching,” Nicholas O’Donnell said.

Michael Keating, a lawyer for other museum members, said if the sale goes forward, Lowy should appoint a special person to oversee the process and ensure the money raised by the museum is used appropriately. The attorney general’s office says it will supervise the sale, but Keating said that’s not enough.

“For the court to approve that, your honor … would be extraordinary under circumstances like that,” he told the judge.