I tried to find the source of that quote, and it seems that the only source anyone knew of was the ‘White House Insider’ website guy. (Ulsterman?). I found someone who did a cut and paste from that website, and it seemed like a hearsay quote to me. I REALLY wish someone would provide definitive proof of its authenticity so i can use all those cool graphics on social media. Please let me know if you ever run across it.
I am a trained historian by trade. Sometimes when you can't find the source you have to look at all of the surrounding information, like intent, outcome, previous activity, etc. Crime detectives do a similar thing looking for who committed the crime.
So, if Jarrett is fulfilling the words that she "supposedly" said chances are she said it and the person who quoted her does not want it to be known who really said it for fear of major retribution.