Tuesday’s special election to determine the size of the Amherst Town Board has been called off.

State Supreme Court Justice Tracey A. Bannister on Wednesday ruled in favor of town Democratic leaders, who were trying to stop a vote that could have kept the board at its current size of six members.

Bannister agreed with Democratic Town Chairman Jerome D. Schad’s argument that Republican board members had no legal basis to call for an “upsizing” election three years after town voters voted strongly to downsize the board from its original seven seats eventually to five.

Bannister called for the referendum to be “stayed until lifted by this or any higher court.”

The judge’s ruling means that – barring a successful town appeal – the scheduled downsizing will take place at year’s end, with one seat trimmed from the board, leaving the final total at five.

Voters approved the downsizing three years ago, but it did not happen immediately. Rather, the town was to “phase out” two seats over the course of three years.

One of the seats was eliminated when former Council Member Barry A. Weinstein became supervisor, and the other is scheduled to be eliminated Dec. 31.

But town Republicans recently changed their minds, arguing that the board has functioned more efficiently with six members than it would with five.

Three Republican seats are up for re-election in November, but not all three incumbents are expected to run, so no one would technically lose a seat. But the victory could still be seen as a win for Democrats who are trying to put a dent in the 5-1 Republican majority in November.

In his arguments, Schad cited the state’s Municipal Home Rule Law, which states that “no local government may restructure its local legislative body … more than once in each decade.”

He also said in court Tuesday that the election should be called off to save town taxpayers the $13,000 to run the special election, a figure Schad said was “woefully underestimated.”

“It makes sense,” Schad said after the ruling. “You shouldn’t be able to change the structure of government every election cycle.”

Town lawyers argued that the state law cited by Schad applied specifically to redistricting issues and not to Amherst’s particular case.

They also downplayed the cost of putting on the election Tuesday, saying the $13,000 figure was “real money” but still small compared with the town’s budget, which exceeds $100 million.

“We believe it to be incorrect and will ask the Appellate Court to review it,” Town Attorney E. Thomas Jones said, adding the town hopes a decision will be made before the November election.

Bannister wrote in her ruling that the cost, in fact, was “not insignificant,” and the election should not go forward regardless of the ruling, as Deputy Town Attorney Patrick M. Kelly had argued.

“Oh my gosh,” he said, before adding, “I’m pleased the court braced the politicians for their self-interested maneuver. I urge the board not to waste taxpayer dollars in an appeal.”