Rep. Peter King (R-N.Y.) was spoiling for a fight.

His family wanted him to do it. He gleefully anticipated a wild ride, international media attention, an Irish blood feud — and a chance to win.

If Caroline Kennedy had been appointed to the Senate, he says, “I would have filed to run a day later.”

But Kennedy’s bid to replace Hillary Rodham Clinton in the Senate famously imploded last week. Instead, Gov. David Paterson (D) — a personal friend of King’s for 20 years — plucked upstate Congresswoman Kirsten Gillibrand (D) for the Senate seat.

King quickly recalibrated. Gillibrand deserves a honeymoon, he told supporters and reporters in the wake of Friday’s announcement. He’ll continue to explore a 2010 Senate bid and decide sometime over the summer, and he expects to fade from the limelight for a little while.

But if the nine-term Congressman knows one thing, it’s New York politics. He’s a junkie, a storyteller with an encyclopedic knowledge of names and races long forgotten. In the days immediately following Gillibrand’s appointment, he detected a perceptible shift.

No one else was granting Gillibrand a honeymoon. Key liberal groups were angry. Congressional colleagues were jealous. Rep. Carolyn McCarthy, whose Long Island district abuts King’s, threatened to run in next year’s Democratic Senate primary because of Gillibrand’s support from the National Rifle Association. Latino legislators in Albany talked openly of finding a primary challenger.

Equally important, King says, Paterson’s standing seems to have “gone into a spiral” over the way he handled the Senate vacancy.

“You only get a chance to make your debut once,” King says of Gillibrand. “You only get one opening act. And hers has been clouded.”

Suddenly, New York Democrats seem nervous, dispirited. And Empire State Republicans, who have been down for so long, may have no place to go but up.

“If the misery of your enemy helps you, that’s a good motivator,” King says.

King isn’t adjusting his timetable for a final decision. But he is adjusting his thinking. He now reasons that of all the possible scenarios for the Clinton succession, absent the daughter of the 35th president, the Gillibrand appointment is the next best thing for him.

“Caroline Kennedy was the easiest to war-game,” King concedes.

But think of the other leading contenders for the Senate appointment. State Attorney General Andrew Cuomo (D)? “Almost impossible” to beat, King says.

Rep. Steve Israel (D), a fellow Long Islander? “It’s hard to know where I’d cut into his support.”

Rep. Carolyn Maloney (D), a Manhattan liberal? Too connected, too strong a fundraiser, “too many ties to the financial industry.”

A poll released Wednesday suggests that Gillibrand could be just as formidable. In a trial heat, the Marist College poll showed Gillibrand leading King, 49 percent to 24 percent. The poll of 611 registered voters, taken Monday, had a 4-point margin of error.

Gillibrand wasn’t widely known in the poll, though her favorable/unfavorable rating was 41 percent to 11 percent. Significantly, she scored higher with Republicans and independents than she did among Democrats.

But Gillibrand, despite her political skills and personal appeal, may still provide King with an opening, especially if New York City Democrats don’t fully embrace her. Gillibrand may attract more support from upstate voters than the average Democrat, but for Democrats, statewide elections are won in the city and its suburbs, and King has at least perfected the formula for winning in a swing suburban district.

“Gillibrand gives me the opportunity to do really well in Nassau, in Suffolk, in Westchester, in Orange, in Rockland, and in the outer boroughs” of New York City, King says.

So will he actually run? That’s the $30 million or $40 million or $50 million question — the price of admission for a viable statewide candidate, and a daunting number by King’s own account. Since arriving in Congress in 1993, King has thought seriously about running for statewide office twice before. Invariably, whenever the governorship or a Senate seat comes open, his name is mentioned as a possible candidate.

This time, national Republican leaders seem content to let King take his time.

“It’s not like we have a really great bench there,” says one Washington, D.C.-based Republican operative.

King says his interest in the Senate race has nothing to do with his frustration at being back in the minority in the House. He still feels he’s able to do important work, particularly on homeland security issues, in the House.

King in fact did run for statewide office once before. Back in 1986, at the age of 42 — the same age Gillibrand is now — while serving as the Nassau County comptroller, he was the GOP nominee for attorney general. He lost to the Democratic incumbent, Robert Abrams, by an almost 2-1 margin.

King says now that he didn’t expect to win back then. His one hope, he figured, was being on the ballot in between the state comptroller’s race and the U.S. Senate race, which were both won by Republicans.

“I thought people would just vote straight Republican and wouldn’t know the difference,” he recalls with a hearty laugh. “Well, they made the decision [to vote for Abrams] anyway.”

But King says the race raised his political profile and taught him how to be savvy about dealing with the cutthroat New York media. “What did I learn? Reporters are much friendlier upstate than they are downstate.”

It’s a joke, but there’s more than an element of truth in the statement. King is now a favorite of the New York media: quick with a quip or a hard-hitting quote, expert on topics that New Yorkers are worried about, like terrorism, and able to deliver his message with the feisty, ethnic, blue-collar sensibility that is increasingly rare in New York these days.

In fact, one D.C.-based Democratic consultant who has worked in New York fears that the media, as much as anything, could be Gillibrand’s undoing in the weeks ahead.

“In any race in New York, there’s always a third opponent in the form of the press,” the Democrat says. “Look at Caroline Kennedy. Caroline Kennedy didn’t have an opponent. It was basically the press. If [editor] Col Allen of the [New York] Post decides he wants to run Gillibrand over, then he will.”

In the end, that’s what it may take for King — or any Republican — to win a Senate race. Despite any jitters and infighting among party leaders, Democrats still reign supreme in New York. In November, they took control of the state Senate for the first time in 46 years. They hold 26 of the state’s 29 Congressional seats. Republicans last won a statewide election in New York in 2002, and they last won a Senate race there in 1992.

In fact, then-Sen. Al D’Amato was the last Republican to win a Senate election, and D’Amato and King go way back. When King first started out in politics in the 1970s, he was elected to the Hempstead Town Council. D’Amato was the town supervisor at the time.

King and D’Amato are so close that the Congressman’s son, Sean, is a vice president at Park Strategies, the former Senator’s lobbying firm. And King sponsored legislation to name a federal office building and courthouse in Islip, N.Y., after D’Amato.

But rather than providing counsel to King on a possible Senate bid, D’Amato was conspicuously at Gillibrand’s side when her Senate appointment was announced last week. King says D’Amato told him that he felt obligated to be there, because Gillibrand was once an intern in his Senate office, and because he is just one of five living current or former New York Senators.

Peter King shrugs at this explanation.

“You never know where Al D’Amato will show up,” he says.