The complaints have piled up for weeks, dismaying many longtime supporters of Gov. Chris Christie of New Jersey and sending others into the arms of his rivals for the presidential nomination, according to interviews with more than two dozen Republican donors and strategists.

As a half-dozen other candidates aggressively raise money and chase endorsements in Iowa and New Hampshire, friends and detractors alike say Mr. Christie’s view of his status and pre-eminence within the Republican field is increasingly at odds with the picture outside his inner circle.

Policy advisers, donors — even a prominent New Jersey state senator who met his wife through Mr. Christie — have all flirted with or committed to rival candidates. One potential donor, Woody Johnson, the billionaire owner of the New York Jets, will back Jeb Bush, according to three people familiar with his plans. Mr. Johnson attended a round of Bush fund-raising events in Chicago on Wednesday, where the former Florida governor acknowledged him by name.