The primary check the president has on Congress is the ability to veto legislation. The president can also choose to implement legislation in a manner Congress did not intend. Executive orders also give the president significant power.
As head of the executive branch, presidents are unable to craft new legislation; all legislation much be passed by Congress. While the president often plays a role in crafting legislation, it is up to Congress to vote on and pass it. However, the president can veto any piece of legislation. This veto power is limited because a two-thirds majority vote in both the House and the Senate will override the veto and make the legislation law. In practice, these votes are rare.
While presidents have a duty to enforce laws, they can also choose how to interpret it. As a result, presidents can often avoid areas of the law they find objectionable. In recent years, so-called "signing statements" have become more popular. These statements outline how the president interprets the legislation.
Congress often has few means of recourse if a president chooses to ignore parts of a law. In practice, this usually means that the president fails to enforce certain laws. Executive orders also allow presidents to exercise power over a limited area of government.