On his Facebook page, Karl Rove writes:

Fifteen new polls in the past seven days have only had a minor effect on the Senate landscape, as Florida moves back from leaning independent to a toss-up. Democrats are still projected to win 49 seats and Republicans 45, but the GOP could take back control of the Senate if they sweep all six toss-up races. Note: after Labor Day, the Rove & Co. forecast will shift from averaging all polls within the past 30 days to all polls within the past 14 days. This shift will allow our forecasts to reflect the increased volume of polling in the fall campaign season. (To download PDF map, visit http://bit.ly/cB61ND)