Presidential right to say "No"

Among the many powers granted the president of the United States is the power to essentially terminate legislation proposed by Congress. This power is outlined in Article I, Section 7 of the U.S. Constitution which states that the president must approve "every bill" and "every order, resolution or vote to which the concurrence of the Senate and House of Representatives may be necessary."
This power is upheld in Article II of the Constitution which discusses the executive powers "vested in a President of the United States."  In Sections 2 and 3 the Constitution details these specific powers. 
This power can be abused by the president however when he has an interest in the bill being voted on.  While the president cannot introduce legislation, he is able to suggest legislation to his party in Congress. 


The Process
The Constitution outlines this process like this:
*The president has 10 days to consider and approve the presented legislation
*There are then 3 options that the president can take:
     1. Sign the bill into a law
     2. Veto the bill
     3. Take no action and the bill automatically becomes law after 10 the 10 day period 
The Presidential veto can be overridden by a 2/3 majority vote of both houses of Congress, which represents the checks and balances system in the government. 
The pocket veto cannot be overridden by Congress. This occurs when Congress adjourns before the 10 day period it is subject to a pocket veto.  

Presidential vetoes from recent years.