New York City Mayor Bill de Blasio faced off with presidential son Eric Trump, warning him that his real estate business could suffer if he doesn’t comply with the city’s newly instituted Green New Deal.

The spat began on Monday after the mayor held a press conference in the Trump Tower lobby to rally around the city’s initiative to combat climate change, making a statement in more ways than one.

“We have passed a mandate in this city requiring buildings to stop the destructive emissions, and that begins with this building right here ― Trump Tower,” de Blasio said. “And clearly the Trump Organization is a little sensitive to the fact that we’re calling them out for what they are doing to the climate and the way this building is a part of the problem, but we will not back down.”

An outraged Trump rebuked de Blasio on Twitter, accusing him of attacking “an iconic organization” and abusing his power for political gain. 

“Spare me,” the mayor shot back. “You and your dad have spent decades evading taxes and stiffing your workers.”

He added, “NYC’s Green new Deal is one law the Trumps won’t get away with breaking. Fix your buildings or pay the price.”

Hitting back at de Blasio, Trump claimed the city had “gone to shit under your leadership,” jabbing his sometimes strained relationship with the police force and stating that crime is up, even though overall, the crime rate has continued to drop.

In response, the mayor delivered a real-time fact check, praising job growth and safer streets, and again cautioning that Trump’s “polluting buildings” would have to change under the new environmental regulations.

The city’s Green New Deal is slated to take effect on Friday and aims to reach carbon neutrality by 2050, requiring local buildings to drastically slash their greenhouse gas emissions under the threat of fines.

According to the city, eight Trump-owned properties in Manhattan will be hit with $2.1 million in penalties each year starting in 2030 if they are not retrofitted to comply with the rules. That includes Trump Tower.

Trump and brother-in-law Donald Trump Jr. both took the reins of their father’s business, The Trump Organization, when he was inaugurated in 2017.

In a press release Monday, the city said the “dirty, inefficient buildings pump approximately 27,000 metric tons of greenhouse gases into our air each year, the equivalent of 5,800 cars.”