New York City Mayor Bill de Blasio declared Thursday that President Trump “will not be welcome back” to the city after he leaves office.

The longshot Democratic presidential hopeful made the comment during BuzzFeed’s Internet Live event at Manhattan’s Webster Hall, where he also challenged the president to a debate.

“I challenge you, Donald Trump, to come to New York City, and I will debate you about what’s right for New York City,” Mr. de Blasio said.

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“Because he doesn’t understand New York City,” he continued. “And when his presidency is over really soon, he will not be welcome back in New York City.”

Mr. de Blasio and Mr. Trump have been trading jabs this week on Twitter over a recent spate of police officers in the city being harassed and doused with water. The president called the suspects’ actions a “disgrace” and called on Mr. de Blasio to “act immediately.”

Mr. de Blasio, who called the harassment “unacceptable,” attacked Mr. Trump for weighing in on the incident and defended New York City as “the safest big city in America.”

“[Mr. Trump] knows NOTHING about his hometown,” the mayor tweeted Thursday. “He never lived a real New York City life. He should get off Twitter and stick to what he’s good at: watching TV when he claims to be working.”