My Republican staffer reader up on the Hill, who likes to keep me honest, writes in to say that I’m calling all the Senate races in the light most favorable to the Dems. I am pointing out Democratic opportunities. That’s true. But if you look at the overall prediction I’m making — that the Dems hold their own or pick up one seat — that assumes that most, or at least many, of the Dem possibles don’t turn into Dem actuals. My point is simply that I’m seeing a growing number of Dem opportunities and only one that looked safe veering toward vulnerability.