Their battleground was some 20 barren acres along the southern side of Delancey Street, where, in 1967, the city leveled blocks of rundown apartment buildings. More than 1,800 low-income families, largely Puerto Rican, were sent packing and promised a chance to return to new apartments someday. Now, nearly 50 years later, the land is still a fallow stretch of weed- and rat-ridden parking lots, though in the waning days of the Bloomberg administration, the city announced that the land would finally be developed into a complex called Essex Crossing, to include retail markets, restaurants, office and cultural space. And new apartments.

Mr. Silver has long characterized his role in plans for the site, known as the Seward Park Urban Renewal Area, or Spura, as limited to insisting that all groups have a voice in the outcome, not promoting a specific plan or developer. “The speaker’s position was always that any development at Spura had to be achieved by consensus among all of the diverse communities that make up the Lower East Side,” his spokesman, Michael Whyland, said in a recent written statement.

But an extensive review of the archives of four mayors and more than two dozen interviews show Mr. Silver and Mr. Rapfogel diligently working behind the scenes to promote specific plans and favored developers. Mr. Rapfogel made clear that the goal was to maintain the area’s Jewish identity, seemingly at the expense of other communities.

Mr. Silver and Mr. Rapfogel steadfastly opposed any mention of affordable housing, which would have altered the demographics of the neighborhood and put Mr. Silver’s political base in question. And Mr. Silver appears to have occasionally misrepresented the desires of his Chinese and Hispanic constituents in conversations with city officials to quash housing plans for the site.

“They’re the reason that this site has been empty for 50 years,” said Edward Delgado, known as Tito, who was a teenager when the city cleared the blocks and his family was evicted. He has been advocating for affordable homes at the site in the decades since.

Mr. Silver and Mr. Rapfogel were born in the neighborhood to Jewish parents. Mr. Silver, 70, grew up in a tenement on Henry Street. His father owned a neighborhood hardware business. Mr. Rapfogel’s father was a clerk for city government.