One of the more bizarre rituals of U.S. politics is the formation by an all-but-announced candidate for some public office of an “exploratory committee.” In California, former governor and current Attorney General Jerry Brown, who was first elected to statewide office 40 years ago — when President Richard Nixon was in the White House — has announced his exploratory committee (what’s left to explore?) for his expected 2010 gubernatorial campaign.

Mark Shields

Mark Shields

These committees are invariably stocked with incurable optimists who, wherever they explore, come back with the same sunny conclusion: Voters overwhelmingly want The Unannounced Candidate to run! Between the presidential election of Sen. John F. Kennedy in 1960 and Sen. Barack Obama in 2008, 36 U.S. senators, after getting a green light from their encouraging exploratory committees, ran unsuccessfully for the White House.

Which brings us to the interesting case of former five-term Memphis congressman and 2006 Tennessee U.S. Senate nominee Harold Ford Jr., who is — without a formal exploratory committee but with the urging of some prominent New York Democratic kingmakers — openly considering a 2010 U.S. Senate race in New York.

Not known for their warmth either to one another or to strangers, New Yorkers welcome outsiders and newcomers when electing U.S. senators. Sens. Robert F. Kennedy, Daniel Patrick Moynihan and Hillary Clinton were born, respectively, in Boston, Tulsa and Chicago. So the fact that Ford is an interloper, or even a carpetbagger, probably will not hurt him with Empire State voters.

There is no 2010 Senate vacancy in New York. The seat to which Secretary of State Clinton was overwhelmingly re-elected in 2006 is now held by former Rep. Kirsten Gillibrand, who was appointed to the Senate by New York Gov. David Patterson.

Full disclosure: I have known and liked Ford since he was a young man. How young? He was elected to Congress at age 26. But in an interview with The New York Times, Ford self-inflicted a wound that could cripple his political chances. This has nothing to do with Ford’s House voting record, which by New York Democrats’ standards might be deemed too conservative.

No, it’s the simple “what kind of a guy are you” query. To the question all red-blooded New Yorkers face about their preference between the Big Apple’s two professional football teams — “Jets or Giants?” — Ford in his answer did not mention any of the Giants greats. No Tiki Barber, Lawrence Taylor or Y.A. Tittle. Nor did the names of revered Jets — Joe Namath, Marvin Powell or Curtis Martin — ever pass his lips.

No, this is what Ford said: “I have breakfast every morning when I am in town … at the Regency. I see my friends the Tisches — Steve Tisch is my close personal friend. I have been to more Giants games. … I had lunch over the holidays with Woody Johnson. We met for the first time. I am happy for his team.”

Why this matters: The Regency is not your neighborhood coffee shop. It’s a luxury hotel in Manhattan. Steve Tisch is the chairman and co-owner of the New York Giants, the man who received the trophy when the Giants won the 2008 Super Bowl. Woody is the owner of the New York Jets.

I am sorry, Harold, but authentic fans’ loyal devotion to their team is not determined alone by who owns that team — or whether they know them socially. Maybe some eccentric tax-phobic conservative who demands a square deal for the Terminally Rich might, but no fans or primary voters living in the Bronx, Staten Island, Queens or Brooklyn.

New Yorkers have demonstrated a high tolerance for carpetbagger candidates for Senate. But anyone who aspires to take a large bite politically out of the Big Apple must first understand that New Yorkers, like the great majority of Americans, root for their favorite team not because of, but in spite of, the people who own them.

Mark Shields is one of the most widely recognized political commentators in the United States. The former Washington Post editorial columnist appears regularly on CNN, on public television and on radio. Click here to contact him.