President Trump scorched fellow New Yorker Bill de Blasio Thursday, just hours after the Big Apple mayor announced his 2020 White House bid, calling the liberal Democrat “a joke” and claiming that “NYC HATES HIM.”

”The Dems are getting another beauty to join their group. Bill de Blasio of NYC, considered the worst mayor in the U.S., will supposedly be making an announcement for president today. He is a JOKE, but if you like high taxes & crime, he’s your man. NYC HATES HIM!” Trump tweeted Thursday morning.

Minutes later, de Blasio hit back, defending his work as mayor, and dubbing Trump with a new nickname– “ConDon.”

“NYC has record low crime & record high jobs. We’re investing in working families with free Pre-K & guaranteed health care. #ConDon taking advantage of working families is no joke. Go to http://BilldeBlasio.com  to join our campaign. As President, I’ll put working people first,” de Blasio tweeted.

The tweets came after de Blasio announced his candidacy early Thursday in a video posted online. De Blasio is the 23rd Democrat to officially announce a bid for the presidency.

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De Blasio touted his experience as a two-term mayor and highlighted his efforts to raise the city’s minimum wage to $15 an hour, approving paid sick leave and creating a comprehensive guaranteed healthcare system.

As president, de Blasio said he would counter many of the controversial policies of the Trump administration, including family separations and backing out of the Paris climate change agreement.

“I will not rest until this government serves working people,” de Blasio said.

But according to a recent Quinnipiac University poll, 76 percent of New York City voters said they did not think de Blasio should run for president, giving him “an anemic 42-44 percent job approval rating.”

On Thursday, following his announcement, de Blasio appeared on ABC’s “Good Morning America,” and was met with dozens of protesters standing outside the studio, some holding foam fingers that said “LIAR,” and signs that read “Mayor Bill de Blasio is no friend of labor.” Some protesters even chanted “liar” outside the GMA studio’s window.

Over the weekend, de Blasio was also met with fierce opposition, during a rally promoting the city’s Green New Deal inside the lobby of Trump Tower, where the mayor threatened Trump’s family company with millions of dollars in fines if his buildings fail to comply with the new environmental standards.

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The mayor, though, was forced to shout for much of his speech amid jeers from a crowd of protesters inside the lobby of Trump Tower. A number of protesters rode up and down the escalator behind de Blasio carrying cardboard signs with slogans like “Worst Mayor Ever,” “Failed Mayor,” and “Trump 2020.”

De Blasio, at the time, said he did not mind the protesters and added that it was “so nice for them to serenade us.”

Meanwhile, in his presidential campaign announcement video Thursday, de Blasio took direct aim at the president, calling him a “bully,” and assuring voters that he knows “how to take him on.”

“Don’t back down in the face of a bully, confront him,” de Blasio said in the video. “Donald Trump must be stopped, I’ve beaten him before and I will do it again.”

Fox News’ Tara Prindiville, Paulina Dedaj, Andrew O’Reilly and Tamara Gitt contributed to this report.