Bob Kerrey has earned a reputation as a principled maverick, which may be part of the reason – along with the weakness of the current Democratic field – that his consideration of a race for mayor caused some rare excitement on the campaign trail.

Yesterday, the former Nebraska senator and current president of the New School released a statement saying it was unlikely he’d run for mayor. But before Mr. Kerrey rules a race out as impulsively as he first floated the idea, he owes it to himself and the city to seriously consider the merits of a mayoral run, either now or in four years.

Running for mayor of New York is nothing to take lightly. It is an enormous investment of time and money and a serious responsibility – the so-called “second-toughest job in the world,” managing a city of 8 million people with a $50 billion annual combined budget.

But Mr. Kerrey has the experience and energy to do it well. His service on the commission that investigated the September 11 attacks, as well as his knowledge of the way Washington works, would make him a formidable leader – a statesman for a global city.

If he entered the race, he would be Mayor Bloomberg’s toughest challenger. That alone should serve as a wake-up call about the relative weakness of the current crop of mayoral hopefuls: Fernando Ferrer, C. Virginia Fields, Anthony Weiner, and Gifford Miller.

Mr. Kerrey was able to offer a better rationale for the replacement of Mayor Bloomberg in five minutes than the current Democratic candidate crop has been able to do in four years. It says a lot about the appeal of a centrist Democrat free from the swamp of local politics running on an anti-tax platform.

With only mild provocation, Mr. Kerrey waxed eloquent on the lack of funding New York gets from Washington, attacking the Alternative Minimum Tax in particular, which effectively eliminates the deduction of state and local income taxes. “I am angry about the way New York City is being treated by Washington, D.C.,” Mr. Kerrey said to the New York Times. “Who is fighting these guys? What would Giuliani and Koch be doing now? They would be raising hell.”

Citing Messrs. Giuliani and Koch, two of the city’s most beloved former mayors, is fighting talk from a seasoned politician who instinctively knows what makes New York tick.

But there are even deeper New York roots in his focus on our imbalance of payments from the federal government. It is a direct response to his friendship with Senator Moynihan, who championed this issue throughout his career.

This is where the inside-baseball element of Mr. Kerrey’s trial balloon becomes a bit interpersonally complicated. Mayor Bloomberg’s communications director, Bill Cunningham, and his campaign chairman, Kevin Sheekey, both were longtime staffers for Senator Moynihan, one of the few Democratic mandarins to endorse Senator Kerrey’s ill-fated 1992 presidential campaign. Together, they were early and vocal Democratic supporters of the need for Social Security reform.

Mr. Kerrey, in turn, served on Mr. Bloomberg’s transition team, advising the incoming administration on appointments. He had informally agreed to serve as honorary chairman of “Democrats for Bloomberg” when he began considering a race of his own.

In the conversation with reporter Adam Nagourney, Mr. Kerrey wisely expressed no personal animosity against Mayor Bloomberg. That is a smart move, because while the mayor is not loved by New Yorkers, neither is he greatly disliked.

The surface logic of a Kerrey campaign run is compelling. Despite the sustained rough and tumble of a Democratic primary, he could make it to a runoff or even clear 40% outright. The current Democratic candidates tiptoed around the possibility of a Kerrey candidacy, signaling his unexpected status as the sleeping giant in this race.

He would cause the greatest problems for the mayor’s re-election by overlapping with most of Mr. Bloomberg’s hoped-for base, while automatically claiming the loyalty of Democrats, who enjoy a 5-to-1 registration advantage in our city. It would force Mr. Bloomberg into a campaign strategy his aides never contemplated and might not be able to effectively fight.

There are no insurmountable logistical hurdles to a Kerrey campaign. He would have at least six weeks to get the necessary number of signatures to appear on the ballot, and the petition process for Democrats in New York is relatively simple.

And while the appeal of electing a Nebraskan who has lived here for less than five years may at first be hard to comprehend, New York voters have traditionally been kind to out-of-staters with a dash of celebrity, including Robert F. Kennedy, Hillary Clinton, and Michael Bloomberg.

Whether or not Mr. Kerrey ultimately decides to run for mayor, the Democratic Party could use him back in the spotlight. He remains one of their most responsible voices. He is authentic, engaging, and not a prisoner of any particular partisan interest.

Mr. Kerrey would be well advised, and the city would be well served, if he kept his options open for the 2009 mayoral race, when his contract with the New School would be winding down and he would have had time to unify the Democratic Party around his candidacy. He would bring some red-state common sense to this blue state city. New York could use such a statesman in City Hall.