Much harder!
One, Warren is a woman and a lot of people are sexist.
Two, Bernie had a good persona going for him. I am talking about all of his attributes combined, including the way he looks, the sound of his voice and his body language, and his name. “Bernie Sanders” happens to be a great-sounding name, the syllables of the name flow well and the first name Bernie is really memorable because it’s uncommon, but it’s also easy to pronounce - look how he became primarily known by his first name. The name Bernie became a brand. Bernie is a character. He looks and sounds like a cartoon character, and has a name like one, and my point is that this is a good thing from a marketing standpoint, not a bad one.
Remember the thing with the bird? Birdie Sanders, instant meme. His name became another meme, Feel the Bern. He had the persona down.
Elizabeth Warren doesn’t have any of that; she does have a nasty nickname that Trump created for her and which will immediately become HER persona if she were the candidate.