The SZ
has a nice piece on the battle to control the U.S. Senate, which is also up for grabs next Tuesday. Who controls the Senate is important because the Senate, in many instances, can directly check the power of the President (treaties, nominations, etc.). But equally important is the fact that the Senate is a co-equal partner with the House of Representative in the legislative process. Put a different way, if one party controls both the House and Senate, that party is more likely to be able to draft bills that they favor.
More importantly, as the SZ points out, who controls the Senate may also determine what the next President can accomplish:
"Zurzeit sind fünf Szenarien denkbar, die zeigen, wie unterschiedlich
groß der mögliche Spielraum für Obama und Romney trotz eines Sieges
sein kann. (see here for the five scenarios)"
