“I think people are about to get scared,” said one aide to a New York official.

The seminal, chilling event, in the end, was simply Ms. Kennedy’s decision to get serious—and go public—with her desire to replace Hillary Clinton in the U.S. Senate.

Specifically, she hired a well-known New York consulting firm with close ties to Chuck Schumer, and began making calls to prominent Democrats around the state, including the man with the power to name Mrs. Clinton’s successor, David Paterson.

At around the same time, Mrs. Clinton—Barack Obama’s pick for secretary of state and arguably the only other official with the public profile to alter the neatly presented narrative of the nascent Kennedy campaign—gave what one of her former aides described as “explicit instructions” to her supporters not to interfere with the process in her name.

In one swift move—the hiring of consultant and former Schumer aide Josh Isay to run her behind-the-scenes bid for the Clinton seat was announced, naturally, by a leak to The New York Times—Ms. Kennedy signaled that far from being an outside celebrity venturing onto the turf of a host of more deserving state and Congressional Democrats, her mission was sanctioned at the highest levels of the state party.

“It’s one of these situations in which the renown of the individual simply clears the field,” said Ross Baker, a political scientist at Rutgers University.

“Maybe she is a better strategic thinker than we giver her credit for—certainly it has worked out,” he said. “I think she has basically eliminated the competition.”

The unofficial announcement of Ms. Kennedy’s intentions followed nearly a week of increasingly loud complaints from members of the New York House delegation, a number of whom also covet the seat (and who doubtless remember being passed over in favor of an outside star the last time a seat was open, in 2000).

The blitz of publicity for Ms. Kennedy instantly overwhelmed those complaints, and at least temporarily collapsed the publicity bubble of the once-talkative attorney general, Andrew Cuomo—also the ex-husband of Ms. Kennedy’s cousin, Kerry Kennedy—who had received lavish credit in the media in recent days for remaining silent about his intentions toward the seat.

As Ms. Kennedy’s detractors are quick to point out, correctly, the decision about Mrs. Clinton’s successor rests solely with Governor David Paterson.

But the powers aligning behind Ms. Kennedy are hard to ignore.

“She has a broad spectrum of support,” said Joel Klein, the city’s schools chancellor, with whom Ms. Kennedy has worked closely, pro bono, in her capacity as a fund-raiser for the city school system.

Several former advisers to Mr. Schumer, for instance, said that it was likely that the company consulting Ms. Kennedy, Knickerbocker SKD, would not have taken her on as a client if Mr. Schumer was opposed to serving with her. The firm’s co-founder, Josh Isay, is a former chief of staff to Mr. Schumer and remains very close with his old boss.

“My assumption is that Josh would have to call to check in,” said a former aide to Mr. Schumer, speaking on background.  

“Josh would probably think twice if Chuck was vehemently opposed to the idea,” said another former aide to Mr. Schumer. “My guess is that he’s not and might even like it.”

Mr. Isay, who also counts Michael Bloomberg as a client, and acted as a consultant for Mr. Cuomo in his disastrous 2002 campaign for governor, did not return a call for comment.

On his company Web site, there is one quotation, prominently displayed: “‘If you need television advertising, direct mail or communications advice, I can think of no better place to go.’ —U.S. Senator Chuck Schumer.”

According to an aide to another New York elected official, Ms. Kennedy’s hiring of Mr. Isay sent a signal to all comers for the appointment that “both the mayor and Schumer had to, at the least, not veto it, and at best, which is more likely, are totally on board with it.”

Referring to the mayor, Mr. Klein said, “I know he thinks highly of her.”

Perhaps just as important as who is backing Ms. Kennedy, is who is not standing in her way. Stories at the end of the week evoked the image of the Clintons activating local New York politicians and officials to try and thwart Ms. Kennedy’s candidacy before it launched. But former aides to Mrs. Clinton said those reports were blatantly false.

“The idea that Caroline Kennedy doesn’t have the experience to be a United States senator is as ridiculous as the argument that Hillary Clinton didn’t have the experience to be United States senator,” said a former aide to Mrs. Clinton, who added that, from a tactical point of view, Mrs. Clinton gained nothing from “picking a fight” with Ms. Kennedy.

“It only hurts,” said the former aide, pointing out that any appearance of injecting herself into politics now could endanger Mrs. Clinton’s appointment to the nonpolitical job of secretary of state.

“The notion that Caroline Kennedy is unqualified is ridiculous; she is absolutely qualified,” said Howard Wolfson, the former communications director for Mrs. Clinton during her presidential and original Senate campaign.

Meanwhile, Ms. Kennedy’s actual critics seemed to be regrouping.

In the days preceding the unofficial announcement, she had been mocked by Representative Gary Ackerman as a political J. Lo, Representative Anthony Weiner suggested to Politico that Clinton supporters still held a grudge against her for supporting Barack Obama in the presidential primary, Democratic National Committeeman Robert Zimmerman used the word “dynasty” on CNN, and plugged-in retail workers union president Stuart Appelbaum released a statement calling her a “blank slate.”

It was all enough to prompt Representative Louise Slaughter, who has since endorsed Ms. Kennedy, to remark that her colleagues in the House were reading off coordinated “talking points” and “were trying to get her out of the way.”

Mr. Appelbaum maintained his dismissive tone.

“The sense you get with Caroline Kennedy is that she is at a point in her life when she is deciding what to do with her life after her children have left for college,” he said.

He said that he was “offended that we look for celebrity rather than substance,” and added, “I think the governor has indicated he doesn’t want people campaigning. I don’t know if there is a Kennedy exception.”

Other critics didn’t immediately react to the big news.

Mr. Weiner, who frequently comments, declined. Even before the announcement, Representative Carolyn Maloney, previously the most outspoken candidate in pursuit of the seat, adopted a more restrained line. Representative Kirsten Gillibrand, who one member of Congress called “second only to Maloney” with the verve she has campaigned, has retreated back below the radar.

Representative Steve Israel, who is often mentioned by supporters in and out of Congress as a candidate for the job, is still actively seeking the appointment, according to a source familiar with his thinking on the matter.

According to the source, Mr. Israel made his interest in the job known to the governor soon after Mrs. Clinton’s official nomination as secretary of state and feels that there is still time to make his case to the governor, despite the Kennedy earthquake.

“This is an audience of one and it’s the governor,” said the source. “This is not an election—it’s an appointment.” 

Randi Weingarten, the leader of the United Federation of Teachers who has also been mentioned by Mr. Paterson as a possible replacement for Ms. Clinton, made a subtle dig at Ms. Kennedy’s educational qualifications. Ms. Weingarten said that she had been a point person in the city’s public schools for more than a decade, then said of her initial chat with Ms. Kennedy, “I’m glad she reached out yesterday.”

Republican Representative Pete King, who is considering running for the seat, said he thinks it will be hard for Mr. Paterson to say no to Ms. Kennedy, given the extraordinary lengths she has gone to show her interest in the position.

“My feeling is right now is that he is going to pick her,” said Mr. King. “I just don’t think she would be doing this much if David hadn’t given her a signal that she was going to be the choice.”

jhorowitz@observer.com