Key Senate races are tightening as candidates on both sides make unexpected gains, suggesting that the final days in the battle for control of the chamber could be as volatile as any in recent memory.

Democrats who were all but written off, including Rep. Joe Sestak in Pennsylvania and Sen. Michael Bennet in Colorado, have revived and are pulling even with their Republican opponents in some polls.

Meanwhile, Republican challengers, including Dino Rossi in Washington and Carly Fiorina…Read More