NEW YORK (CBS News) — Former New York Mayor Michael Bloomberg formally announced he is running for the Democratic presidential nomination on Sunday, launching a multimillion-dollar ad campaign that frames his candidacy as the best hope for defeating President Trump.

In a letter on his revamped website, Bloomberg wrote that the country “cannot afford four more years of President Trump’s reckless and unethical actions.”

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“[Pres. Trump] represents an existential threat to our country and our values. If he wins another term in office, we may never recover from the damage,” Bloomberg wrote.

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