The New York Times has the story:
Mr. Bloomberg, 73, has already taken concrete steps toward a possible campaign, and has indicated to friends and allies that he would be willing to spend at least $1 billion of his fortune on it, according to people briefed on his deliberations who spoke on the condition of anonymity because they were not authorized to discuss his plans. He has set a deadline for making a final decision in early March, the latest point at which advisers believe Mr. Bloomberg could enter the race and still qualify to appear as an independent candidate on the ballot in all 50 states.