Larry Sabato’s Crystal Ball is currently projecting a seven-seat pick up for the Republicans. The Rothenberg Political Report gives the Republicans between five and seven pick ups, with eight “certainly possible.” Congressional Quarterly predicts the Republicans will take at least four seats away from the Democrats, and judges four others as toss ups. On the other hand, four Republican seats are also rated as toss ups by CQ.
The latest betting on Intrade markets looks for the Republicans to pick up four Democratic seats. The Intrade markets give the Republicans about a 12% chance of controlling the Senate.
Finally, RealClearPolitics figures the Republicans will take seven seats, based on current polling data.