Former New York City Mayor Michael Bloomberg slammed President Trump in an op-ed over the weekend written for his own media outlet, Bloomberg News.

Bloomberg, a potential 2020 presidential candidate, said that Trump is becoming "increasingly isolated," noting the upcoming departure of Defense Secretary James Mattis.

He wrote that Mattis' resignation, the partial government shutdown and the recent stock market drop were due to "Trump's recklessly emotional and senselessly chaotic approach" to his presidency.

"At the halfway mark of this terrible presidency, one has to wonder how much more the country can take," Bloomberg said.

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Trump said in October that Bloomberg would "be easy" to defeat if the former mayor got the Democratic nod in 2020.

“I think the Democrats will eat him up,” the president said during the interview with Fox Business’ Trish Regan.

In his op-ed, Bloomberg added that unless congressional Republicans "start showing some spine," the remainder of Trump's first term in office could be enough to test if the country can sustain his "model of bad government."

Bloomberg told the Associated Press in November that early next year would be "about as late" as he could decide whether or not to run in 2020.

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