THE decision by William Bratton to step down as New York police commissioner leaves an uncertain void in a city that has just begun to enjoy an improved sense of safety.
In less than three years on the job, Mr. Bratton has come to represent a symbol of security for New Yorkers. He has been given credit for taming the city's stubborn crime rate by transforming the way police think about their jobs and communities.
His announced departure March 26 - largely as a result of a pique with Mayor Rudolph Giuliani - underscores the growing problem of revolving-door police chiefs in some of the nation's largest cities. It also points up the clashes that can go on between City Hall and the precinct house in an era of dwindling resources to fight crime.
Ironically, Bratton's departure may have been hastened by how well he did in curbing crime - or, at least, in taking credit for curbing crime. His success generated a popularity that was the envy of politicians, and many local pundits blame that, in part, for the tension that has grown up between Bratton and Mr. Giuliani.
''He's one of the great commissioners, and he'll long be remembered,'' says former Mayor Ed Koch, who blames Bratton's ''hurried'' departure on Giuliani's interference in the department's management and his resentment of Bratton's popularity. ''[Giuliani] made it difficult for him to enjoy his job,'' Mr. Koch says.
Bratton has been consistently more popular than Giuliani. In a poll conducted in February by the Quinnipiac College Polling Institute, Bratton's favorability rating stood at 54 percent, compared with Giuliani's, at 44 percent.
''There's always tension between top officials and the people that appoint them,'' says Maurice ''Mickey'' Carroll, the Quinnipiac College Polling Institute director. ''Both of these guys like to be out front.''
But Mr. Carroll also noted that Giuliani benefited from Bratton's success. The mayor's overall job performance was improved by New Yorkers' favorable assessments of his handling of crime.
''People didn't like the way [Giuliani] handled the budgets, schools, but crime, bingo, 3 to 1 in favor,'' Carroll says.
During Bratton's short tenure, serious crime in New York dropped by 27 percent. Homicides alone were down almost 40 percent. Bratton is also credited with routing out the deep-seated corruption in one of the city's more notorious precincts.
Giuliani's supporters say that it is precisely because crime is so important in New York that the mayor needs to replace Bratton now, before next year's mayoral election.
''It's not enough in New York City to fight crime and to do it well, there's always politics,'' says Jay Severin, a Republican political consultant based in New York. ''It is not Bratton's crime fighting credentials that were ever at issue here. It's a matter of political loyalty.''
Mr. Severin says the mayor cannot afford to go into an election year with a police commissioner that he has any reason to believe is not totally committed to the mayor, and his political agenda.
''It is the worst-kept secret in the city that among Bratton's other impressive credentials is not the political loyalty to the mayor,'' says Severin, who believes Giuliani will see short-term political fallout, but in the long run neither he nor the city will lose from Bratton's departure.
Other disagree. Koch says he's indignant that Giuliani would put an insistence on political loyalty above the quality of Bratton's job performance and its impact on the city.
''Bratton recently tried to elevate a black commander and the Giuliani people said, 'No.' You know why? Because Bratton hadn't publicly declared his allegiance to the mayor,'' says Koch. ''I find that to be vile myself.''
But Koch also believes the improvements made by Bratton won't necessarily disappear with him. And Severin argues that, in fact, a police commissioner that is more solidly behind the mayor, will have more success in building on Bratton's gains.
''This is New York,'' says Severin. ''You can't discount the importance of politics.''