Story highlights Bloomberg's pitch is unusual as it's not coming from a party stalwart

The former New York mayor once considered an independent bid for the White House himself

Philadelphia (CNN) Former New York City Mayor Michael Bloomberg offered Hillary Clinton his resounding endorsement Wednesday night, emerging as her most prominent independent surrogate as he tore into fellow billionaire businessman Donald Trump.

Speaking on the third night of the Democratic National Convention in Philadelphia, Bloomberg slammed Trump's business record and called the Republican nominee a "dangerous demagogue" who must be stopped in an explicit appeal to independent voters across the country.

"When I enter the voting booth each time, I look at the candidate, not the party label," Bloomberg, who has had various political affiliations, said in his prime-time speech. "There are times when I disagree with Hillary Clinton. But let me tell you, whatever our disagreements may be, I've come here to say: We must put them aside for the good of our country. And we must unite around the candidate who can defeat a dangerous demagogue."

Bloomberg used his perspective as a businessman, New Yorker and former mayor to hit Trump from multiple angles.

"I'm a New Yorker, and New Yorkers know a con when we see one," he said to cheers from the audience.

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