Just eight months after taking office, Mr. Christie is in demand by Republican candidates across the country, political consultants say, receiving many more invitations than he can accept. His appearances with Ms. Whitman are the first of many he has scheduled over the coming weeks, including events Thursday with Susana Martinez, the Republican candidate for governor of New Mexico, and a trip next week to Ohio…

Questions about presidential ambitions, and the governor’s emphatic denials, have become a standard feature of his interviews.

But some political analysts expressed doubt that Mr. Christie’s visits would have much effect on his public profile across the country, or on the candidates he backs. Still, such events get the attention of Republican activists, “the people who write checks and stuff envelopes and are delegates to a national convention,” Dr. Green said.