Almost immediately there was speculation that Kennedy withdrew as a face-saving measure after Paterson informed her that he was going to choose someone else. But Kennedy associates say they were convinced that Paterson was going to offer the job to the daughter of JFK.
"He was offering her the seat," said one confidant. "There's no doubt about that."
Ted Sorensen, former special counsel and adviser to President John F. Kennedy, told ABCNews.com that he believes the daughter's reason for dropping out had to do with her desire for privacy.
"Kennedy all her life has, like her mother, cherished first and foremost her family and her privacy," said Sorensen.
"She would have been foolish not to try the tempting dessert of a political career which so many people she knows and are related to have tried," he said. "But having briefly tried it she has gone back to her first priorities -- family and privacy."
"I'm not going to say anything to violate that privacy," Sorensen added.
One source close to Kennedy told ABC News that she called the governor to back out because she was made aware of a personal situation that was going to make her unable to accept the Senate seat.
Paterson asked Kennedy if she'd rather take some time to think about it, and she agreed, the Kennedy source said. But by 11 p.m., she had called Paterson back to say the personal situation was preventing her from taking the job.
Kennedy adviser Josh Isay would not specify what "personal reasons" had caused Kennedy to bow out, referring to her written statement.
The turnabout also came as her uncle Ted Kennedy, the family patriarch and a leader in the Senate, recuperated from seizures stemming from his treatment for brain cancer. The source told ABC News that Ted Kennedy's health was not factor that prompted her to abandon the Senate quest.
When Kennedy announced two months ago that she was interested in being appointed to Clinton's vacated seat, she immediately vaulted to the front of the pack of politicians vying to become New York's second senator, a job once held by her slain uncle Robert Kennedy.
During her brief campaign around the New York, she cited her pedigree as well as her family's history of public service.
"You know, from a family that really has spent generations in public service. … I feel this commitment, this is a time when nobody can afford to sit out," she said.
Kennedy's exit from the race was as shocking as her entrance. At the time she announced her interest in the position, a handful of veteran politicians were jockeying for the post, including New York Attorney General Andrew Cuomo, who was once married to Kennedy's cousin Kerry.
Cuomo, also a member of Democratic royalty, may now be the most prominent candidate contending for the post. Cuomo is the son of former Gov. Mario Cuomo, a man who was once considered a presidential contender.
Others who have been mentioned as names on Paterson's list include Rep. Kirsten Gillibrand, Rep. Carolyn Maloney, Rep. Steve Israel and city teachers union President Randi Weingarten.
There were indications as recently as last Friday that Paterson may not have made up his mind on his choice for Clinton's successor.
A spokesman for Maloney said that as recently as Friday, Paterson had called Maloney and had not ruled out her bid for the Senate seat.