need in a post-trump world. we need to galvanize, not polarize. reporter: buttigieg taking a jab at senator elizabeth warren. we will fight when we must fight. but i will never allow us to get so wrapped up in the fighting that we start to think fighting is the point. reporter: biden echoing that message, criticizing the progressive candidate s approach on health care. these guys are saying my way or the highway. reporter: warren hit back, and without naming them targeted biden. unlike some candidates for democratic nomination, i am not counting on republican politicians having an epifny. reporter: and buttigieg. we know a number of people who raised a quarter of a million dollars for him, his quote national inverts circle. and he offers them regular phone