The President of the United States is the head of government and state in the United States. The President is the leader of the federal executive branch and the Commander in Chief of the United States military. The 44th and current President of the United States is Barack Obama.
One of the duties of the President is to sign bills into law or to reject them by issuing a veto, both of which take place after a bill has passed both chambers of the United States Congress. If the bill is vetoed, a two-thirds majority in both chambers of Congress can override the veto. Otherwise, the bill does not become a law.
If the Stop Online Piracy Act, the PROTECT IP Act, or a variation of the two passes both chambers of Congress, the President is responsible for signing it or vetoing it. Should the bill pass in 2012, President Obama will be responsible for this.