New York City Mayor Bill de Blasio staged a chaotic news conference in the lobby of Trump Tower on Monday in which he touted a city anti-pollution law, was heckled by President Donald Trump’s supporters and said he will announce this week whether he’s running for president.

Speaking at a podium steps from the spot where Trump announced his own run in 2015, the Democrat said he had come to warn the president that Trump Organization buildings could face a combined $2.1 million in annual fines by 2030 if they don’t comply with a new law requiring skyscraper owners to cut greenhouse gas emissions.

“President Trump, you’re on notice. Your polluting buildings are part of the problem,” he said.

But de Blasio’s speech was all-but drowned out by a throng of Trump supporters who demonstrated behind him on the building’s escalators, booing, whistling, chanting and holding up signs with messages including, “Failed mayor” and “Worst mayor ever.”

New York Mayor Bill de Blasio was heckled by Trump supporters as he unveiled a new environmental policy at Trump tower pic.twitter.com/Il41pFYTNO

— Bloomberg Originals (@bbgoriginals) May 13, 2019

Loud music also played over the building’s sound system for part of the event. De Blasio had to shout to be heard over songs including a Frank Sinatra rendition of “I’ve Got You Under My Skin.”

“It’s so nice of them to serenade us at Trump Tower. Clearly, they are uncomfortable with the truth,” he said.

Under a deal Trump struck with the city decades ago, the skyscraper’s lobby is considered a public space for much of each day.

Responding to a reporter’s question, De Blasio — still straining to be heard — said he was discussing a possible presidential run with his family.

“We will make a final decision this week and we will announce it this week,” he said.

The Climate Change Denier-in-Chief went on @FoxNews to call New York City’s #GreenNewDeal crazy. Why’s @realDonaldTrump so scared?

Because he’s part of the problem and he knows it. pic.twitter.com/YNS2AjnVvl

— Mayor Eric Adams (@NYCMayor) May 13, 2019

De Blasio, who is in his second term as mayor, has openly discussed his desire to run for several months and has made exploratory trips to several early primary states.

De Blasio said he initially intended to hold Monday’s news conference outside Trump Tower but moved it indoors because of the weather. As for the hostile reaction inside the tower, he said he wasn’t concerned.

“One of the things you have to be when you’re mayor is unflappable,” he said. “You can’t let anything bother you because you have to make tough decisions all the time. So, as I say, this is music to my ears.”

Scene in lobby of Trump tower as Trump supporters try to drown out de Blasio rally with signs saying “worst mayor ever” pic.twitter.com/5xo7wYpHKI

— Melissa Russo (@MelissaRusso4NY) May 13, 2019

De Blasio takes his Green New Deal fight to Trump Tower today. Under new city law Trump Org (and many other developers) could owe millions in fines starting in 2030 if they down cut emissions in their buildings. pic.twitter.com/BWPoTLiZEL

— Grace Rauh (@gracerauh) May 13, 2019

.@realDonaldTrump is running scared from NYC’s Green New Deal. The temper tantrum his organization threw at Trump Tower today is proof.

You're on notice, Donald: we won't let you mortgage our future for your real estate. Fix your buildings or pay the price.

We WILL collect. pic.twitter.com/3wHT4gr2km

— Mayor Eric Adams (@NYCMayor) May 13, 2019

We joined climate activists to take New York City’s Green New Deal into the heart of Trump Tower.

Trump’s employees tried to drown us out. But New York City doesn’t back down.@realDonaldTrump: no polluting landlord is above the law in this town. Especially not you.

— Mayor Eric Adams (@NYCMayor) May 13, 2019

Never back down in the face of a bully. Our planet is worth the fight. #GreenNewDeal

— Mayor Eric Adams (@NYCMayor) May 14, 2019

We know we're doing something right when @realDonaldTrump sends his cronies to try to shout us down — and they just learned the hard way that New Yorkers don't back down from a fight.

New York City's #GreenNewDeal is bold, audacious and necessary. pic.twitter.com/Vhd8OiwGa9

— Mayor Eric Adams (@NYCMayor) May 13, 2019

Trump Tower will face nearly a half a million dollars in fines if they don't cut their emissions under NYC’s Green New Deal.
Every big building owner is on notice: cut emissions or face real consequences. pic.twitter.com/AFjrCbxhki

— NYC Mayor's Office (@NYCMayorsOffice) May 13, 2019

Spare me. You and your dad have spent decades evading taxes and stiffing your workers.

NYC’s Green New Deal is one law the Trumps won’t get away with breaking.

Fix your buildings or pay the price. https://t.co/NZdqbWQF7T

— Mayor Eric Adams (@NYCMayor) May 13, 2019

(AP)