Bloomberg became NYC mayor on the GOP ticket. NYC Republicans amount to 13% of its voters. Bloomberg presumably won a majority of their votes, and a fair chunk of Democratic votes, against the Democratic nominee. He spent $650m on becoming mayor and simply donating money to get things done as mayor that he couldn't get appropriated by the City Council, while taking $1 a year in salary. I expect he will outspend both parties combined by billions to run for office. Total campaign spending by Obama and Romney amounted to $1b. Bloomberg is worth $40b via his financial data service (Bloomberg) which, from a zero base, went on to crush his rivals Reuters and Thomson.
Bloomberg is a pro amnesty gun grabber with the personality of a robot. He is also a midget. I saw a picture of him standing next to Trump that was truly embarrassing.