ccording to the latest numbers from Public Policy Polling, Democrat Elizabeth Warren is leading incumbent Republican Scott Brown in the Massachusetts Senate race. Warren and Brown have taken turns playing the frontrunner since the race begin, and Warren's current lead is only slight, about 5 percentage points. Still, Brown's approval rating is low: 45 percent versus 42 percent who disapprove of the job he's done so far. When only Republicans are polled, however, his approva