People tended to snicker when, on Feburary 8, 2006, we issued an editorial under the headline “Bloomberg for President?” And we don’t mind saying that we’ve enjoyed watching one paper after another, from the New York Times to the Washington Post to the Chicago papers and those on the Coast, start to take the idea seriously, even as the mayor has continued to deny that he has plans to run. We haven’t endorsed Mr. Bloomberg for president, and we have plenty of quarrels with him over policy. But with each passing week the logic of a Bloomberg candidacy has grown clearer and the idea of it more exciting, and when the mayor disclosed yesterday that he was changing his registration to independent, there was nary a snicker anywhere to be heard.

On the contrary, our sense is that the more the Republican and Democratic parties conduct their autophagy — the Republicans, save for Mayor Giuliani and at times Senator McCain, running away from their president and the Democrats, save for Mrs. Clinton, seeking to best one another at appeasement — the more attractive becomes the prospect of a candidacy on the kind of principles the mayor is evincing. It’s not the abjuring of partisanship that is his trademark so much as the problem-oriented focus, non-breast-beating management style, and — even more importantly — a willingness to work with almost anyone to get goals accomplished. On that last point, he’s sometimes gone too far, by our lights, working with such demagogues as Lenora Fulani and the Rev. Al Sharpton. But from the long perspective, he has made an astonishing success of politics.

And he seems to be enjoying it enormously, a point we made in “Bloomberg for President?” He started out an amateur. He worked with exceptional diligence. He failed on a number of initiatives, including an ill-thought-out effort to try to sideline political parties as a matter of law and institute something called non-partisan elections. But he got up from his defeats and went on to win an extraordinary mandate for a second term. And he has guided the city he governs into what may be its greatest period of growth and optimism. Crime is down, investment is up, a real estate boom of historic proportions is underway, and there is everywhere in his realm a sense of dynamism. The mayor is laying strategic plans to guide growth and improvement in the city for generations to come.

We take nothing away from Mayor Giuliani, whose achievements as mayor were phenomenal, from the conquest of crime, to the restoration of confidence that the city can be governed, to his heroic performance in the hours and weeks after the attacks of September 11, 2001. But Mr. Bloomberg ‘s own achievements are no less. He entered office just days after the fires of the World Trade Center were finally extinguished, and as a wounded city lay stunned. Who could have imagined that the next mayor could bring crime down even further? Or launch a building boom the likes of which the city has seen only a few times in its history, and seize the lead of the urban debate in the country? And emerge at the center of planning for a post-Sarbanes-Oxley economy? And do it while making almost no enemies? Even people whom the mayor drives crazy with his nanny-state policies tend to like him.

Now it must be said that many of the gains that the mayor has been able to show as mayor owe an enormous debt to the policies of President Bush, particularly the president’s tax cuts, which have ignited the great national boom of which New York City is a part. There is also the president’s determination, at enormous political cost, to stay on the offense in the war against Islamist terror and fight our enemies on their own ground rather than here in the city and elsewhere in America. The mayor could be more generous in his acknowledgements. But the Republicans could learn from the ease with which Mr. Bloomberg moves among the leaders of business and, for that matter, labor, at home and abroad. And the creativeness with which he is seeking a synthesis on growth and the environment.

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The mayor, in any event, has his work cut out for him if he wants to get into the presidential race. It’s one thing to complain, as he did on the Coast this week, about the quality of the debates. It’s another to seize the lead on certain issues and to seize ones that are bigger than illegal guns and the nation’s eating habits. Yet it strikes us that there are issues out there made to order for him, or vice versa. He is mayor of the city that has a greater appreciation of the glories of immigration than any other in America, and the mayor has been magnificent on the issue. The two parties are completely at loggerheads on the subject, and it is an opportunity for Mr. Bloomberg to bring to the debate everything that New York has to offer plus his own well-proven pragmatism and management abilities.

Also out there for him are the health care debate, the deadlock on taxes, and even the war. The mayor has no record as a war leader, though he has — in combination with Commissioner Kelly — kept the city safe on his watch. Mr. Giuliani will challenge the mayor on these topics. But Mr. Bloomberg moves with great ease on the international stage, partly because before he entered politics he employed more foreign correspondents than most newspapers employ in total. If we had to guess what he might bring to this area it would be a recognition that, while staying on the offense in the war is essential, the war is only a part of the international story. There is an international competition to be entered on business climate, a currency to protect, and a dynamism to be extended, and the stage is now set for Mr. Bloomberg to make his next move.