The sun was not yet up yesterday, and members of Senator Hillary Rodham Clinton’s campaign team were confronted with the kind of attack that most infuriates them: one questioning the character of Mrs. Clinton and her husband.

To make matters worse, it came from David Geffen, the Hollywood executive who was once a big supporter of the Clintons but has since turned on them and is now backing Senator Barack Obama for the Democratic presidential nomination.

What followed was a remarkably caustic exchange between the Clinton and Obama campaigns that highlighted the sensitivity in the Clinton camp to Mr. Obama’s rapid rise as a rival and his positioning as a fresh face unburdened by the baggage borne by Mrs. Clinton, the junior senator from New York. The Clinton camp seemed also to be sending a warning to mudslinging critics that they would be dealt with fiercely.

It began with a column in The New York Times by Maureen Dowd, in which Mr. Geffen said the Clintons lie “with such ease, it’s troubling” and that the Clinton political operation “is going to be very unpleasant and unattractive and effective.” Mr. Geffen called Mr. Clinton a “reckless guy” who had not changed in the last six years, and suggested that Mrs. Clinton was too scripted.