I'VE SAID it before: There's a fine line between an outraged reformer who challenges the status quo and the whiner who keeps blaming others for his problems, and the toes of Martin O'Mayor's shiny shoes are right there on the line again. This week he's knocking the U.S. attorney for Maryland for not helping to fight crime here in the City of a Few Dozen Charms, and, being grateful for small favors, we happily note how Mr. O'Mayor this time resisted slamming a prosecutor with profane anger -- as he did the city state's attorney, Pat Jessamy, last year.

Maybe it's a sign of maturity. We don't know yet. They're still running tests.

But it's worth recalling that when Jessamy dropped charges against an allegedly corrupt cop because she believed the case against him was a loser -- key evidence was compromised in that goofy burglary of a "secret" police office -- Martin O'Malley was heard to say: "She doesn't even have the goddamn guts to get off her ass and go in and try this case. ... Maybe she should get the hell out and let somebody else in who's not afraid to do the goddamn job."

Intemperate?

Yeah, well, at the time, I heard a lot of people -- white people, in the main, and many of them not even city residents -- say they appreciated O'Malley's anger against Jessamy, an African-American who's been state's attorney since 1995. ("I think our mayor is doing a great job," a woman from Bel Air said on a radio call-in show.) They found O'Malley's profane attack as refreshing as Zima -- no matter how disingenuous it might have been.

I recall a decidedly different reaction among African-Americans and others who recognized a political cheap shot when they heard one. (O'Malley, a law school graduate, apparently wanted Jessamy to prosecute the cop even though she believed the evidence against him had been tainted.)

Now, it's Thomas M. DiBiagio, mild-mannered federal prosecutor for a major metropolitan area, catching heat from O'Mayor.

A story in this newspaper the other day reported that suspects arrested for shootings and other serious gun crimes are less likely to be convicted and more likely to receive shorter jail terms than they were two years ago.

That's not good news for the City That Bleeds, but gun-crime prosecution is a complex issue. Cops are under pressure to make lots of arrests. Sometimes they bring to the state's attorney's staff cases with slim evidence or witnesses who vanish or change their stories. There have been changes in sentencing guidelines, too, and that apparently accounts for some of the drop in jail time.

O'Malley, who has staked his political future on a record of crime reduction in Baltimore, could have accepted responsibility for this trend or conceded that breaking the cycle of violent crime is going to take more time than he and his police commissioner have had.

Look, the O-Man is on an extended political honeymoon. Elected in 1999, he's still widely favored in this town, so much that most Baltimoreans don't want him to run for governor. They think he's good for the city, that he gives people throughout the metropolitan area confidence in Baltimore's future. I agree.

So O'Malley could have just said: "Getting guns out of the hands of criminals is a tough job. I'm not going to knock our police officers for bringing too many cases, but obviously the evidence has to stick or the arrests are a waste of time and resources."

Most Baltimoreans would have accepted that, and those of us weary of O'Malley's blame game -- blaming judges, blaming Jessamy, blaming the feds, blaming the FBI, blaming the ACLU -- would have heard it as a promising change of tune.

Instead, O'Malley reached over to the federal courthouse on Lombard Street to lay blame there. He blasted DiBiagio.

If only the "cowardly" feds took more gun cases, we wouldn't have these problems, O'Malley said.

Of course, one might ask: If the problem is cops bringing flimsy cases or not following up on gun arrests with more investigation, or if witnesses disappear or change their stories, what difference will jurisdiction make? A loser case in state court is a loser case in federal court, isn't it?

There still seems to be general agreement: O'Malley is good for this city. But, one of these days, the honeymoon is going to end, and he'll have spent all his credibility in these fits of hyperbole and frat-house sarcasm, if not profanity. Pithy sound-bites are great, but government-by-criticism doesn't seem smart in the long run. At some point the genuine outrage of a reformer just sounds like the whine of a man blaming others.