Senate Majority Leader Harry Reid (D-Nev.) and Minority Leader Mitch McConnell (R-Ky.) engaged in a heated hour-long exchange over filibuster rules on the Senate floor Thursday, and by the end of the day, McConnell said Reid risked becoming the worst Senate leader in history.

If Reid goes through with the so-called nuclear option, McConnell said, "our friend the majority leader is going to be remembered as the worst leader here ever."