Public Advocate Bill de Blasio and tenants took on the landlord of an upscale Midtown apartment building, one of the last buildings to refuse to sign onto a contract for city doormen.

Tenants alleged the building's conditions have slowly deteriorated since doormen went on strike.

Garbage is not taken out and strangers have been let in, according to tenants.

"It's this basic message to William Koeppel: Do your duty, take care of your tenants, come back to the table and resolve this situation. That's your job. It's time to do your job," said de Blasio.

The landlord, William Koeppel, is a former fundraiser for former Mayor Rudolph Giuliani who pleaded guilty to soliciting contributions from tenants in exchange for rent-regulated leases in the 1990s.

He denied the tenants' allegations and said he is currently negotiating a new contract for doormen.