Albany, N.Y. ? Caroline Kennedy’s mysteriously abrupt decision to abandon her Senate bid gave rise to an ugly swirl of accusations Thursday and feverish speculation over whether she jumped or was pushed.

The 51-year-old daughter of President John F. Kennedy was widely considered a front-runner for the Senate seat until she sent a midnight e-mail to reporters and Gov. David Paterson saying she was withdrawing for what she described only as personal reasons.

Even though many Democrats had thought Paterson was going to appoint Kennedy any day now, a person close to the governor said Thursday that Paterson had no intention of picking her because he believed she handled herself poorly in introducing herself as a candidate.

The person also said there were concerns about possible tax problems for Kennedy, a potential “nanny problem” involving a housekeeper, and media rumors that her marriage was on the rocks. The person, who spoke on condition of anonymity because he said he wasn’t authorized to speak for the governor, would not elaborate.

Kennedy spokesman Stefan Friedman would not detail her reasons for withdrawing, but complained: “This kind of mudslinging demeans that process and all those involved.”

The state tax department said it could not find any problems with Kennedy’s tax records. In a December interview, she denied she had any “nannygate” problem and said that her husband, Edwin Schlossberg, was very supportive and that they lived together with their children.

On Thursday, Paterson issued a statement in which he said Kennedy’s decision “was hers alone.” He is expected to announce his choice for the Senate today.