The House of Representatives and the Senate, the two chambers of the U.S. Congress that make up the legislative branch of government, can override a presidential veto. This may result in a bill becoming a law without the president’s approval.
If the president vetoes a bill and Congress is in session, he sends the unsigned bill back to Congress with a veto message explaining why it was rejected. Congress then has the opportunity to re-evaluate it. Two-thirds of the members of the House and Senate are required to override the veto. When Congress is not in session, the president can reject a bill by refusing to acknowledge it in an action called a pocket veto. Congress does not have the authority to override a pocket veto.