Harris can beat Nelson. Her numbers are in good shape given that most people only know her from the 2000 election recount. She will be able to beat Nelson. Just getting an R in the seat isn't enough. As an example, I cite our own Mel Martinez's lackluster perdormance to date.
Nelson said he would fillibuster any attempt to even consider drilling offshore on any coast. I don't want just any R in there either, and Martinez may still come around. If she can win, she's an ideal choice, but sometimes these early numbers move around some during the campaign, but then end up about where they started on election day.