Three times during the third quarter earnings conference call with journalists and analysts last week, Ford CEO Alan Mulally was asked to comment on persistent reports that he is considering leaving the automaker to become CEO at Microsoft.

And three times, Mulally gave variations on the same reply he’s been giving since the reports surfaced in early September.

“We don’t comment on speculation. We have no change to our plan,” Mulally responded when an analyst opened the question and answer session of the Oct. 24 conference call by asking him to comment on the media reports. The plan, announced by Ford in November 2012, calls for Mulally to stay until the end of 2014.

A little later in the call, an Associated Press reporter put the question a different way: “Have you spoken to Microsoft about the CEO position?”

Again Mulally’s response: “There’s nothing that has changed about our plan we announced last November and I’m excited and honored to serve Ford.”

But the question still wouldn’t die. When another reporter brought it up a third time, Mulally became more terse: “Our plan has not changed. Thank you.”

A Ford insider tells me both Mulally and Chairman Bill Ford are extremely frustrated by this ongoing line of inquiry.

But as long as Microsoft keeps searching for someone to succeed retiring CEO Steve Ballmer, and as long as Mulally will neither confirm nor deny his interest in the job, he’s likely to keep hearing the questions.