You’ve probably heard by now that Sarah Palin this week was unwittingly duped into taking a phone call from a guy claiming to be French President Nicolas Sarkozy when in fact it was really a Canadian comedian well known for pulling pranks on celebrities and other well-known politicos.

So how exactly did that happen? According to a senior McCain aide, the caller made initial contact with Palin’s advisers by first calling the governor’s office in Alaska. The call had been routed through France, and the comedian used the name of one of Sarkozy’s top aides, which suggested the phone call was legitimate. “He did all the right things,” this aide insists. The message was passed on by Palin’s aides back in Alaska to the McCain campaign and was ultimately routed up the food chain, ending up in the hands of Steve Biegun, a former National Security adviser to President Bush, who is now one of Palin’s top aides. Seeing no warning signs, Biegun and other top McCain aides signed-off on the call, and the rest is history.

Privately, McCain aides see the phone call as more of an embarrassment for the staff than for Palin—after all, it’s up to the staff who gets to talk to the candidates and who doesn’t. But that may be lost on voters who already have doubts about Palin’s experience and readiness for the office.

UPDATE, 4 PM EST:

A second senior McCain aide clarifies what exactly the campaign knew about the call. According to this aide, none of McCain’s top staffers were aware of the call between Palin and the fake Sarkozy until after the fact. The call was routed from Palin’s Alaska office directly to the advisers working directly with the GOP VP hopeful, and they made the decision to initiate contact without notifying other members of McCain’s senior staff. Upon word of the fake-out, the campaign’s upper echelon organized a conference call yesterday afternoon with both McCain and Palin senior aides to discuss how to handle. According to one participant, who declined to be named, aides went back and forth venting their frustration. “Does anyone not think it’s strange that the French president would want to talk to a candidate in the final 72 hours of the campaign,” one senior McCain aide demanded, noting that the White House and the National Security Council would likely be involved in any such phone calls. “It’s appalling.” Bigger picture, the episode provides a glimpse at what have been increased tensions between the McCain plane and the Palin plane in the final weeks of the campaign. Aides have pushed back in recent days against stories that all is not well between the two camps, but it appears that may not be exactly true.