Her campaign for an appointment to the senate seat vacated by Hillary Rodham Clinton started with a halting rollout and ended this past week in a spectacular implosion - marred at the end by accusations leveled by someone close to the governor.
Kennedy is telling friends she won't be stepping away from the public sphere entirely, although it remains unclear what path she might take. Rumors abound that, given her early endorsement of now-President Barack Obama, she could land a federal appointment.
In a matter of months, America's dominant image of the daughter of slain President John F. Kennedy was transformed from that of the adorable little girl riding a pony on the White House lawn to that of someone more complicated - a woman who remained connected to her father's Camelot legend but who was now forging a bumpy public path of her own.
She drew fire throughout her campaign. Critics questioned her experience and accused her of profiting off her family name. She was attacked for declining to answer questions, then was lampooned for giving interviews replete with conversational fillers such as "um" and "you know."
Some accused her of not explaining clearly enough why she wanted the job, while others worried she seemed ill at ease under the spotlight and questioned if she could win election to the seat in 2010.
Friends and supporters maintained that the 51-year-old Kennedy was driven by a passion for public service. They argued that the unconventional path she had followed allowed her to build a resume as a fundraiser, mediator and legal thinker - all skills they said would help her excel on Capitol Hill.
Kennedy herself cited her "relationships" in Washington, and supporters believed her friendship with Obama and her closeness with her uncle, Sen. Edward Kennedy, would smooth her way.
Associates said her verbal glitches had never gotten in the way of her reputation as a brilliant mind and gifted writer.
But early Thursday, she confirmed she had dropped out of contention, and on Friday Gov. David Paterson announced he was appointing Rep. Kirsten Gillibrand - a little-known Democrat from a rural upstate district - as Clinton's successor.
Kennedy's decision to withdraw played out messily Wednesday over hours of conflicting accounts in which she apparently wavered in her determination to win the seat, ending with a terse, one-sentence e-mail to reporters after midnight in which she cited "personal reasons" for her withdrawal.
On Thursday, a person close to the governor claimed she was facing possible tax and "nanny" problems, and there were media rumors that her marriage was on the rocks. A Kennedy spokesman complained that the mudslinging demeaned what had been a fair process.
The governor eventually said in a statement that no candidate had been disqualified by vetting.
The bitter back-and-forth caused at least short-term damage to Kennedy's image - and may have reflected even more poorly on Paterson.
One Kennedy friend involved with the process said later that Kennedy had a "minor issue with a nanny" that the governor's staff reviewed and found to be irrelevant. The friend, who spoke on condition of anonymity because of the sensitivity of the situation, also said Kennedy had a minor, $615 city tax lien that she settled in 1994 and no other tax problems.
The friend, who's been speaking with her nearly daily in recent weeks, said Kennedy had expressed a desire to continue looking "for ways to serve."
"She would like to serve in some capacity, but it's a little too fresh to know what that capacity might be," the friend said.
Sen. John Kerry, D-Mass., said Friday he had spoken to Kennedy and was sorry she wouldn't be taking the New York seat, which once was held by another Kennedy uncle, Robert F. Kennedy.
"I think she really was put in a very difficult position, almost impossible one, but she'll go on to do terrific things," he said. "She just made a personal decision for a number of reasons this is not the right way to do it and it's not the moment to do it, and I can understand that."
Kerry even speculated that she might still one day run for office.
That would shock Muzzio, after what he called "the trashing that she's suffering from the Paterson folks." But Lee Miringoff, director of the Marist College poll, said Kennedy could still have a shot.
"She would have to regroup, but people have come back from worse," he said.
The longer she waits, the more the power of the Kennedy mystique will fade, argued Rutgers University politics professor Ross Baker, who noted that few younger voters feel the Camelot-era pull toward her family.
"The Kennedy appeal has become kind of quaint," he said.
If Kennedy returns permanently to private life, she could continue her fundraising work on behalf of New York City's public schools or move into an under-the-radar advisory role, akin to the job she had as a member of Obama's vice presidential search team.
But Kennedy has long acted as one of the primary tenders of her family legacy - writing and editing books that have helped to keep alive the Kennedy mystique and working to guide family efforts such as the selection of the John F. Kennedy Profile in Courage Award winners. With that history and her professed passion for contributing to political and social change, she may not be willing to fade into the background.
Writers for The Washington Post and at least one British newspaper wondered whether she might follow in the footsteps of her grandfather, Joseph Kennedy, as the U.S. ambassador to the United Kingdom.
Many have suggested Obama might offer such a post or another appointment in part out of gratitude for her endorsement during the Democratic primary contest, which came at a key moment in his showdown with Clinton.