Chris Christie announced his resignation as New Jersey's top federal prosecutor last week and promptly admitted to considering a run for governor. In the state's political circles, Christie's tenure has been seen - and, among his fellow Republicans, advertised - as a prelude to a gubernatorial campaign.

That risks shortchanging Christie's achievement over seven years as U.S. attorney. By making an unavoidable issue of the state's corruption crisis, Christie has already done more good for New Jersey than some previous governors.

Christie's crusade was partly a matter of emphasis. The U.S. Attorney's Office has long been New Jersey's foremost - if not only - public-corruption watchdog. But Christie drew special attention to corruption cases, offering pointed commentary on specific convictions and the general problem, cultivating the media, and keeping a running tally of his public-official pelts.

But Christie's record has been remarkable in substance as well as bluster. His office successfully prosecuted more than 130 public officials. And it has not lost a single corruption case.

The count includes some low-level public employees, but it also features an array of (now former) political movers. Among the highest-profile convictions were Sharpe James, the longtime Newark mayor and state senator; John Lynch, a former state Senate president and Central Jersey power broker; James Treffinger, who was Essex County executive and a U.S. Senate contender; Charles Kushner, a top fund-raiser for former Gov. Jim McGreevey and other Democrats; and Wayne Bryant, the powerful state senator from Camden County who was found guilty last week.

Christie's blitzkrieg helped create an environment where once-impossible reforms became possible. The past seven years have seen a Legislature notoriously averse to reform agree to restrict campaign contributions, the holding of multiple offices, and pork-barrel spending.

That's not to give Christie all of the credit for those and other measures. But by marching a long parade of mayors and lawmakers off to federal prison, his office made it harder for reactionaries to keep pretending that reforms weren't necessary. At one point last year, virtually the entire Legislature seemed to be under federal investigation.

Democratic accusations that Christie has been a partisan prosecutor don't hold up. While he has prosecuted more Democrats than Republicans, he has also operated during a period of statewide Democratic dominance. And he has overseen more than token prosecutions of GOP officials.

It's true that Christie has not always been careful about matters of politics and ethics. He has at times crossed the line into inappropriate politicking in his speeches and appearances. And he showed a significant ethical blind spot in awarding a lucrative federal monitoring contract to the firm of his onetime boss, former Attorney General John Ashcroft.

So Christie is not without blemishes. But he has shaken up the state's political establishment for the better, in the way that only an outsider could. Ironically, much the same can be said of his potential rival next year, Gov. Corzine.

Would Christie make a good governor? That could be next year's question. There's no question, though, that he was an excellent prosecutor.