The U.S. Senate is considered to be the most powerful second chamber in the World for the following reasons. It is the only legislative house which enjoys direct executive powers. It shares with the President the power of making top-ranking appointments and through this privilege, it controls the internal administration of the Federal government.
The Membership of the Senate is small but has a long tenure of 6 years. Thus the Senators are not worried about their election and can do full justice to the policy and programs of the Party.
The Senate enjoys equal powers in legislative and financial spheres. In India, England etc., the upper house is given lesser authority than the Lower house in the spheres of legislation. But in the US both the Senate and the House of Representatives enjoy equal powers in case of ordinary and financial legislation.