The factors are:

i. The Senate’s exclusive powers of appointment confirmation and treaty ratification are often of considerable consequence for the political system.

ii. The Senate delivers the final verdict in impeachment proceedings.

iii. Senators have six year terms, compared to the two year terms of the House.

iv. The Senate’s exclusive powers are more significant, especially the ratification of treaties and the confirmation of presidential nominees.

v. The frequent use of the filibuster and the consequent need for a 60 vote ‘supermajority’ mean that the passage of legislation is more problematic than in the House, and gives senators of both parties a degree of leverage.

vi. The increased use of the filibuster, and the consequent need for a ‘super-majority’ to pass almost any legislation, means the president’s legislative strategy is usually focused on the Senate.