While New York City Mayor Bill de Blasio sought to influence federal policy at the Democratic National Convention in Philadelphia, back at City Hall, his top housing officials strove to solidify his legacy.

On Tuesday, Alicia Glen, deputy mayor for housing and economic development, said the city started the process of building and preserving 23,284 homes during the last fiscal year, which she said represented an unprecedented sustained generation of below-market homes.

Technically, the city created 25,000 affordable housing units under former Mayor Ed Koch. But Glen argued the record represented an unusual “blip,” and that the Koch administration was not facing many of the challenges the de Blasio administration is forced to navigate: a shortage of city-owned land, an increasingly expensive real estate market and a federal government that’s more reluctant to finance related projects.

“What we have now is two and one-half years of sustained production at levels never before seen, and again, when we don’t necessarily have the same raw ingredients that the Koch folks had,” Glen told reporters. “We are in an amazing place.”

Additionally, city Department of Housing Preservation and Development Commissioner Vicki Been pointed out the poorest New Yorkers were more likely to benefit from this administration’s efforts. Historically, Been said, about 2 percent of the city’s housing efforts targeted those making less than $18,000 a year or $24,000 for a family of three. Despite more heavily subsidized homes being harder to finance, Been said the de Blasio administration aimed to ensure 8 percent of the units it created were reserved for those with the lowest incomes. Since 2014, 13 percent of the units created under de Blasio have been reserved for that group, Been said.

“Right now, what the numbers show to me and to all of us in the industry is that we’re (firing) on all cylinders now,” said Gary Rodney, president of the city’s Housing Development Corporation, which helps finance subsidized housing projects. “This machine is something that we put in place – the mayor set the tone, and we were charged with a huge task.”

The city started constructing 6,097 new affordable homes and preserving 17,187 others during the recently concluded fiscal year 2016. The numbers show a 28 percent decline in the number of new units the city launched from the 8,485 started in fiscal year 2015. City officials said the drop occurred because several developers rushed to get their applications in before the 421-a tax abatement ended in fiscal year 2015 and did not indicate a construction slowdown. In fact, a housing spokesman said, new construction work was up since the lapse of 421-a, the benefit meant to spur developers to set aside a portion of their projects for affordable housing. De Blasio’s goal of creating 200,000 units of affordable housing over a decade was drafted assuming the existence of 421-a, but Glen said the city still believes it can complete the plan without it.

She and others pointed out that more and more private developers are expected to set aside part of residential projects for affordable apartments under a new zoning template. This Mandatory Inclusionary Housing policy applies whenever a landlord requests the city’s consent to build larger than allowed by the current zoning code – or whenever an area is rezoned to allow for denser development. Additionally, the officials said they had several other tools to incentivize the creation of below-market-rate housing at their disposal.

But with such a sunny outlook, why didn’t de Blasio want to spread the good news himself?

Glen said helping to make New York’s former U.S. Sen. Hillary Clinton the first female president required his presence at the Democratic National Convention, but promised he would spend the next month hashing out his housing plan at events and ribbon cuttings across the city.

“He’ll be hitting the neighborhoods,” Glen said.