With less than a month until New York City’s decades-old tax abatement program is set to expire, a coalition of groups looking to reform 421-a has grown 2.5 million people bigger.

Up4NYC, an group advocating for changes to the program, announced this morning that they now have the backing of the NYC Central Labor Council, the Building and Construction Trades Council, and the New York State AFL-CIO.

This comes as many groups push for either an extension of the current 421-a program, or a complete revamp to the tax relief program.

“It is simply unacceptable to continue putting the interests of wealthy developers ahead of working families,” said Mario Cilento, president of the New York State AFL-CIO, in a statement. “The economic impact of the public dollars used could be much more significant if we demand policy changes to the 421a program. The focus should be on requiring middle class wages for working families and expanding access to affordable housing.”

NYC Mayor Bill de Blasio unveiled a plan earlier this month to improve the program. Under his plan, 25-30 percent of a project’s units would be dedicated to lower-income residents in exchange for tax breaks. His plan also pushes a “mansion tax” on sales of homes costing more than $1.7 Million.

Up4NYC is calling for a similar plan with an added provision. For construction workers involved in 421-a projects, they’d like to see a prevailing wage. That’s a move that some say could limit new projects under the 421-a program due in part to larger expenses.

The coalition also wants more units dedicted to affordable housing, but does not place a specific number.

The group has released two ads in the last month, pushing for reform to the program rather than a complete revamp. Others want the program done away with, saying money saved from ending the tax breaks could go to help low-income residents.

Here’s their latest ad from last week: