By Erica Orden 

ALBANY--Gov. Andrew Cuomo on Wednesday threw his support behind a proposal to provide a property tax break to New York City victims of superstorm Sandy who have rebuilt their homes, backing a key request by Mayor Bill de Blasio to the state Legislature.

The tax break provided a moment for the two Democrats to find common ground, after months of squabbles over issues such as charter schools and how to fund expanded prekindergarten.

The legislation, as described at a Sandy rebuilding conference in the Capitol complex, is intended to reduce property-tax bills for about 1,500 New York City property owners who have rebuilt or repaired their homes after Sandy. They would face an increase this year because the fixes boosted the homes' value.

The legislation, which Mr. de Blasio said has been drafted but hasn't yet been introduced, requires the support of the Legislature and the governor, whose approval the mayor described as crucial.

"Folks who have finally gotten their homes back together did it after immense struggle and in most cases immense personal expense, and we want to make sure they're not set back yet again, so this legislation will give them immediate relief," Mr. de Blasio said.

With Mr. Cuomo's backing and that of the legislative leaders, the proposal is likely to sail through Albany, but its timing remains an important question. The city is scheduled to send out property-tax bills in about a month, and if the legislation isn't passed by then, the city would have to refund money to individual homeowners who receive and pay the higher bills--a potentially messier process than amending their bills beforehand.

Mr. de Blasio said that he was optimistic the legislation would pass in time but added that if even the refund process becomes necessary, "either way you slice it, the same amount of money will be returned to their hands."

The governor's backing of Mr. de Blasio's plan stood in contrast to their recent skirmishes over other mayoral proposals, most notably increasing taxes on the wealthy to pay for pre-K in New York City. In their formal remarks at the event, Messrs. de Blasio and Cuomo trotted out their now-familiar anecdotes about their personal and professional relationship over the past two decades.

At a separate event later, the mayor addressed some of the disputes he has had with Mr. Cuomo this year. "Well, you know, life is long," he said. "When you have a relationship of that depth and history, it doesn't matter if sometimes you disagree. There's plenty more things you agree on."

Noting some of the successes he achieved in the state budget, like state funding dedicated to expanding full-day prekindergarten in the city, Mr. de Blasio added: "I always say the product is what you really need to measure by, and the product of this relationship is in a very good place."

Mr. Cuomo addressed the possibility that federal officials may spend more than $1 billion of the remaining $3.6 billion of rebuilding aid on disasters other than Sandy, calling it "ironic" that members of Congress who didn't support the funding allocation in the first place are "trying to come and poach it."

The U.S. Department of Housing and Urban Development--which is administering that pot of money--has said the congressional legislation authorizing billions of dollars in Sandy aid required that some of it be spent on disasters in other states.

Mr. Cuomo sided with New York lawmakers who disagree.

"That money was appropriated for New York, New Jersey," the governor said. "We think it would be disingenuous if the money did not go to the place it was intended for in the first place."

Write to Erica Orden at erica.orden@wsj.com