Have you listened to her speak?
I thought JT would be a fantastic speaker (in the vein of that great orator, Obama), until I heard him deliver a few speeches  that might have been less rehearsed, and responses to media questions.
"Uhhh" and "ummm" seemed to be his favourite phrases.

In contrast, Ambrose can deliver polished, coherent, and engaging responses to media questions, and strong speeches even with light preparation.