Here’s a cool map and accompanying data from pollster.com. It includes predictions based on a reasonable averaging of the available polls. It shows the Rs with 49 senate leads and 4 toss-ups. That would mean 51 seats? Well, no, because the D candidate has a slight advantage, if truth be told, in each of the toss-up states: MD, VA, MT, and MO. So 50 is still the most informed calculation.