She remains unpopular with independents as well, and some Republicans. She has a LOT of work to do, much like Hillary did in NY in 2000, but in a much less one-sided state.
The latest polling shows the race at 46% for Nelson, 39% for Harris. That is really very good shape for someone who just announced running up against an imcumbant. Surely, if Jeb announced he would have a lead, but I think barring Jeb, Harris is the best chance.