By this time in 2005, Bloomberg had spent $9.8 million and had not begun advertising. In the early months of his campaign that year, most of his money went toward polling and building an extensive voter database.
This year, the mayor began advertising on television in April. His ads, which are popping up all over the airwaves, focus mostly on the economy.
The mayor is also spending millions on consultants, polling and salaries for his staff. And he takes care of small expenses for his campaign staffers, like parking tickets and many of their meals. He has already spent tens of thousands of dollars on food, including hundreds on Chinese takeout and barbecue for the office.
Bloomberg is shattering his own spending records amid what appear to be extremely favorable conditions for his re-election.
His approval rating has hovered in the 60s for several years - even while he makes budget cuts and proposes recession-era tax hikes.
Campaign spokesman Howard Wolfson defended the mayor's spending, saying the point is to engage voters in a dialogue.
Plus, he added, "we are not taking anything for granted."
It isn't even clear yet who he's running against.
The field of Democratic challengers shrank after the mayor changed term-limits law last year so that he could run again.
One would-be challenger, U.S. Rep Anthony Weiner, says he is rethinking his plans, while the leading Democratic candidate, William Thompson Jr., is so plagued with whispers that he will drop out that he often has to address the rumors at his own campaign appearances.
Thompson's spokeswoman, Anne Fenton, said Bloomberg "is spending almost 19 million dollars to try to convince New Yorkers that they need 4 more years of higher taxes, rising unemployment, record homelessness and overcrowded schools."
Both Weiner and Thompson rely on donations and public matching funds to finance their campaigns. They have raised about $10 million between them.
In public opinion surveys, voters have said they are not bothered by Bloomberg's eye-popping campaign spending. A Marist College poll out this week found an overwhelming majority of respondents did not care how much he spends.
Bloomberg, whom Forbes magazine ranks as the 17th richest person in the world with an estimated wealth of $16.5 billion, does not take donations or public money. He can spend freely but must disclose his campaign spending according to the same deadlines as the candidates who accept public financing.
Friday's deadline was the second this year, covering the period of March 12 to May 11. In that time, Bloomberg spent $15.7 million; in the first filing period he spent $2.9 million.
The founder of the financial information company Bloomberg LP spent a total of $85 million on his last re-election bid, which ended in a landslide victory.
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